Needles and systems for radiofrequency neurotomy

ABSTRACT

Apparatus for radiofrequency neurotomy are disclosed. Needles with deployable filaments capable of producing lesions at target volumes, which include a target nerve, and systems including such needles are disclosed. Ablation of at least a portion of the target nerve may inhibit the ability of the nerve to transmit signals, such as pain signals, to the central nervous system. The lesion may facilitate procedures by directing energy towards the target nerve and away from collateral structures. Example anatomical structures include lumbar, thoracic, and cervical medial branch nerves and rami and the sacroiliac joint.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/092,945, filed Apr. 7, 2016, titled SYSTEMS AND METHODS FOR TISSUEABLATION, which is a continuation of U.S. patent application Ser. No.13/101,009, filed May 4, 2011, titled SYSTEMS AND METHODS FOR TISSUEABLATION, which claims priority benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 61/347,351, filed May 21, 2010,titled METHODS AND SYSTEMS FOR SPINAL RADIO FREQUENCY NEUROTOMY, U.S.Provisional Patent Application No. 61/357,886, filed Jun. 23, 2010,titled INTERVERTEBRAL DISC HEATING, and U.S. Provisional PatentApplication No. 61/357,894, filed Jun. 23, 2010, titled LARGE FIELDDIRECTIONAL RADIOFREQUENCY NEUROABLATION, each of which is incorporatedherein by reference in its entirety.

BACKGROUND Field

The present application generally relates to thermal ablation systemsand methods, and more particularly to systems and methods for radiofrequency (RF) neurotomy, such as spinal RF neurotomy.

Description of the Related Art

Thermal ablation involves the creation of temperature changes sufficientto produce necrosis in a specific volume of tissue within a patient. Thetarget volume may be, for example, a nerve or a tumor. A significantchallenge in ablation therapy is to provide adequate treatment to thetargeted tissue while sparing the surrounding structures from injury.

RF ablation uses electrical energy transmitted into a target volumethrough an electrode to generate heat in the area of the electrode tip.The radio waves emanate from a non-insulated distal portion of theelectrode tip. The introduced radiofrequency energy causes molecularstrain, or ionic agitation, in the area surrounding the electrode as thecurrent flows from the electrode tip to ground. The resulting straincauses the temperature in the area surrounding the electrode tip torise. RF neurotomy uses RF energy to cauterize a target nerve to disruptthe ability of the nerve to transmit pain signals to the brain.

SUMMARY

This application describes example embodiments of devices and methodsfor tissue ablation, such as spinal radio frequency neurotomy. Systemsinclude needles with deployable filaments capable of producingasymmetrical offset lesions at target volumes, which may include atarget nerve. Ablation of at least a portion of the target nerve mayinhibit the ability of the nerve to transmit signals, such as painsignals, to the central nervous system. The offset lesion may facilitateprocedures by directing energy towards the target nerve and away fromcollateral structures. Example anatomical structures include lumbar,thoracic, and cervical medial branch nerves and rami and the sacroiliacjoint.

In some embodiments, a needle comprises an elongate member having adistal end, a tip coupled to the distal end of the elongate member, anda plurality of filaments. The tip comprises a bevel to a point. Theplurality of filaments is movable between a first position at leastpartially in the elongate member and a second position at leastpartially out of the elongate member. The plurality of filaments and thetip are configured to transmit radio frequency energy from a probe tooperate as a monopolar electrode.

In some embodiments, a needle comprises an elongate member having adistal end, a tip coupled to the distal end of the elongate member, anda plurality of filaments. The tip comprises a bevel portion comprising apoint on a side of the elongate member. The plurality of filaments ismovable between a first position at least partially in the elongatemember and a second position at least partially out of and proximate tothe side of the elongate member. The plurality of filaments and the tipare configured to transmit radio frequency energy from a probe tooperate as a monopolar electrode.

In some embodiments, a needle comprises an elongate member having aproximal end and a distal end, a tip coupled to the distal end of theelongate member, a plurality of filaments, and a filament deploymentmechanism coupled to the proximal end of the elongate member. The tipcomprises a bevel portion comprising a point. The plurality of filamentsis movable between a first position at least partially in the elongatemember and a second position at least partially out of the elongatemember. The plurality of filaments and the tip are configured totransmit radio frequency energy from a probe to operate as a monopolarelectrode. The filament deployment mechanism comprises an advancing hub,a spin collar, and a main hub. The advancing hub includes a stem coupledto the plurality of filaments. The spin collar includes a helical track.The stem of the advancing hub is at least partially inside the spincollar. The main hub comprises a stem comprising a helical threadconfigured to cooperate with the helical track. The stem of the main hubis at least partially inside the spin collar. The stem of the advancinghub is at least partially inside the main hub. Upon rotation of the spincollar, the filaments are configured to move between the first positionand the second position.

In some embodiments, a needle comprises an elongate member having adistal end, a tip coupled to the distal end of the elongate member, anda plurality of filaments. The tip comprises a point. The plurality offilaments is movable between a first position at least partially in theelongate member and a second position at least partially out of theelongate member. The plurality of filaments and the tip are configuredto transmit radio frequency energy from a probe to operate as amonopolar electrode. A single wire comprises the plurality of filaments.

In some embodiments, a needle comprises an elongate member having adistal end, a tip coupled to the distal end of the elongate member, anda plurality of filaments. The tip comprises a bevel to a point. Theplurality of filaments is movable between a first position at leastpartially in the elongate member and a second position at leastpartially out of the elongate member. The plurality of filaments and thetip are configured to transmit radio frequency energy from a probe tooperate as a monopolar electrode. The tip comprises a stem at leastpartially in the elongate member. The stem includes a first filamentlumen, a second filament lumen, and a third lumen. The bevel portioncomprises a fluid port in fluid communication with the third lumen.

In some embodiments, a needle comprises an elongate member having aproximal end and a distal end, a tip coupled to the distal end of theelongate member, a plurality of filaments, and a rotational deploymentmechanism coupled to the proximal end of the elongate member. The tipcomprises a bevel to a point. The plurality of filaments is movablebetween a plurality of positions between at least partially in theelongate member and at least partially out of the elongate member. Thedeployment mechanism comprises indicia of fractional deployment of theplurality of filaments relative to the tip. The plurality of filamentsand the tip are configured to transmit radio frequency energy from aprobe to operate as a monopolar electrode.

In some embodiments, a needle comprises an elongate member having adistal end, a tip, and a plurality of filaments. The tip comprises afirst body portion and a second body portion. The first body portionincludes a tapered portion and a point. The tapered portion includes aplurality of filament ports. The second body portion is coupled to thedistal end of the tip. The second body portion is at an angle withrespect to the first body portion. The plurality of filaments is movablebetween a first position at least partially in at least one of the tipand the elongate member and a second position at least partially out ofthe filament ports. The plurality of filaments and the tip areconfigured to transmit radio frequency energy from a probe to operate asa monopolar electrode.

In some embodiments, a method of heating a vertebral disc comprises:positioning a distal end of a needle in a posterior annulus; deploying afilament out of the needle; traversing the posterior annulus fromlateral to medial; applying radio frequency energy to the tip and to thefilament; and ablating pain fibers in the posterior annulus.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member, anactuator interconnected to the plurality of filaments, and a lumen inthe elongate member. The tip is shaped to pierce tissue of the patient.Movement of the actuator relative to the hub moves the plurality offilaments relative to the tip. The lumen and the tip are configured toaccept an RF probe such that an electrode of an inserted RF probe, thetip, and the first and second filaments are operable to form a singlemonopolar RF electrode.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member in aretracted position, and an actuator interconnected to the plurality offilaments. The actuator is operable to move the plurality of filamentsrelative to the hub, the elongate member, and the tip between theretracted position and a fully deployed position. In the fully deployedposition, the plurality of filaments extends outwardly and away from thetip. Each filament comprises a distal end that defines a point in thefully deployed position. Each point is distal to the distal end of theneedle. The average of all the points is offset from a centrallongitudinal axis of the elongate member.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member in aretracted position, and an actuator interconnected to the plurality offilaments. The actuator is operable to move the plurality of filamentsrelative to the hub, the elongate member, and the tip between theretracted position and a deployed position. In the deployed position,the plurality of filaments extends outwardly and away from the tip. Eachfilament comprises a distal end that defines a point in the deployedposition. Each point is distal to the distal end of the needle. Eachpoint is on a common side of a plane that contains a centrallongitudinal axis of the elongate member.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member in aretracted position, and an actuator interconnected to the plurality offilaments. The plurality of filaments consists of a first filament and asecond filament, and the needle contains no filaments other than thefirst and second filaments. The actuator is operable to move theplurality of filaments relative to the hub, the elongate member, and thetip between the retracted position and a deployed position. In thedeployed position, the plurality of filaments extends outwardly and awayfrom the tip. Each filament comprises a distal end that defines a pointin the deployed position. Each point is distal to the distal end of theneedle. In the deployed position, a midpoint between the distal end ofthe first filament and the distal end of the second filament is offsetfrom a central longitudinal axis of the needle.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member in aretracted position, and an actuator interconnected to the plurality offilaments. The plurality of filaments consists of a first filament and asecond filament, and the needle contains no filaments other than thefirst and second filaments. The actuator is operable to move theplurality of filaments relative to the hub, the elongate member, and thetip between the retracted position and a deployed position. In thedeployed position, the plurality of filaments extends outwardly and awayfrom the tip. Each filament comprises a distal end that defines a pointin the deployed position. Each point is distal to the distal end of theneedle. In their respective deployed positions, each distal end definesa vertex of a polygon. A centroid of the polygon is offset from acentral longitudinal axis of the needle.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member in aretracted position, and an actuator interconnected to the plurality offilaments. The plurality of filaments consists of a first filament and asecond filament, and the needle contains no filaments other than thefirst and second filaments. The actuator is operable to move theplurality of filaments relative to the hub, the elongate member, and thetip between the retracted position and a deployed position. In thedeployed position, the plurality of filaments extends outwardly and awayfrom the tip. Each filament comprises a distal end that defines a pointin the deployed position. Each point is distal to the distal end of theneedle. In their respective deployed positions, each of the plurality offilaments points in an at least partially distal direction.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member in aretracted position, and an actuator interconnected to the plurality offilaments. The plurality of filaments consists of a first filament and asecond filament, and the needle contains no filaments other than thefirst and second filaments. The actuator is operable to move theplurality of filaments relative to the hub, the elongate member, and thetip between the retracted position and a deployed position. In thedeployed position, the plurality of filaments extends outwardly and awayfrom the tip. Each filament comprises a distal end that defines a pointin the deployed position. Each point is distal to the distal end of theneedle. When the plurality of filaments are in the deployed position,portions of each filament extend outwardly away from the tip. Eachportion of each filament extending outwardly away from the tip isstraight.

In some embodiments, a needle for insertion into a patient during an RFablation procedure comprises a hub, an elongate member fixed to the hub,a tip fixed to the elongate member at a distal end of the needle, aplurality of filaments in at least a portion of the elongate member in aretracted position, and an actuator interconnected to the plurality offilaments. The plurality of filaments consists of a first filament and asecond filament, and the needle contains no filaments other than thefirst and second filaments. The actuator is operable to move theplurality of filaments relative to the hub, the elongate member, and thetip between the retracted position and a deployed position. In thedeployed position, the plurality of filaments extends outwardly and awayfrom the tip. Each filament comprises a distal end that defines a pointin the deployed position. Each point is distal to the distal end of theneedle. When the plurality of filaments is in the deployed position, thetip comprises an angle of at least 200 about the central longitudinalaxis of the elongate member that is free of filaments.

In some embodiments, a method of performing spinal RF neurotomy in apatient comprises moving a tip of a needle to a first position proximateto a target nerve along the spine of the patient, after achieving thefirst position, advancing a plurality of filaments relative to the tipto a deployed position, and after the advancing step, applying RF energyto the tip and plurality of filaments, wherein said applying generatesheat that ablates a portion of the target nerve.

In some embodiments, a method of performing lumbar RF neurotomy on amedial branch nerve in a patient comprises: moving a tip of a needle toa first position between the transverse and superior articular processesof a lumbar vertebra such that an end point of the tip is proximate to asurface of the vertebra; after achieving the first position, advancing aplurality of filaments relative to the tip to a deployed position; andafter advancing the plurality of filaments, applying RF energy to thetip and the plurality of filaments. Said applying generates heat thatablates a portion of the medial branch nerve.

In some embodiments, a method of performing sacroiliac joint RFneurotomy in a patient comprises: a. moving a tip of a needle to a firstposition proximate to a sacrum of the patient; b. advancing a pluralityof filaments relative to the tip to a first deployed position; c.applying RF energy to the tip and plurality of filaments, wherein theapplying generates heat that ablates a first volume; d. retracting theplurality of filaments; e. with the tip in the first position, rotatingthe needle about a central longitudinal axis of the needle to re-orientthe plurality of filaments; f. re-advancing the plurality of filamentsrelative to the tip; and g. re-applying RF energy to the tip andplurality of filaments, wherein the re-applying comprises ablating asecond volume proximate to the tip, wherein a center of the first volumeis offset from a center of the second volume.

In some embodiments, a method of performing thoracic RF neurotomy on amedial branch nerve in a patient comprises: moving a tip of a needle toa first position proximate a superior surface of a transverse process ofa thoracic vertebra such that an end point of the tip is proximate tothe superior surface; after achieving the first position, advancing aplurality of filaments relative to the tip toward a vertebra immediatelysuperior to the thoracic vertebra to a deployed position; and afteradvancing the plurality of filaments, applying RF energy to the tip andthe plurality of filaments, wherein said applying generates heat thatablates a portion of the medial branch nerve between the thoracicvertebra and the vertebra immediately superior to the thoracic vertebra.

In some embodiments, a method of performing cervical medial branch RFneurotomy on a third occipital nerve of a patient comprises: a.positioning the patient in a prone position; b. targeting a side of theC2/3 Z-joint; c. rotating the head of the patient away from the targetedside; d. locating the lateral aspect of the C2/3 Z-joint; e. moving,after steps a, b, c and d, a tip of a needle over the most lateralaspect of bone of the articular pillar at the juncture of the C2/3z-joint to a first position contacting bone proximate to the mostposterior and lateral aspect of the z-joint complex; f. retracting,after step e, the tip of the needle a predetermined distance from thefirst position; g. extending, after step f, a plurality of filamentsoutwardly from the tip and towards the lateral aspect of the C2/3z-joint such that the plurality of filaments are positioned straddlingthe lateral joint lucency and posterior to the C2/3 neural foramen; h.verifying, after step g, the position of the tip and filaments byimaging the tip and a surrounding volume; and i. applying, after step h,RF energy to the tip and the plurality of filaments, wherein theapplying generates heat that ablates a portion of the third occipitalnerve.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention aredescribed herein. Of course, it is to be understood that not necessarilyall such objects or advantages need to be achieved in accordance withany particular embodiment. Thus, for example, those skilled in the artwill recognize that the invention may be embodied or carried out in amanner that achieves or optimizes one advantage or group of advantagesas taught or suggested herein without necessarily achieving otherobjects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription having reference to the attached figures, the invention notbeing limited to any particular disclosed embodiment(s).

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are described with reference to the drawings of certainembodiments, which are intended to illustrate certain embodiments andnot to limit the invention.

FIG. 1 is a schematic diagram of an RF neurotomy system being used toperform RF neurotomy on a patient.

FIG. 2A is a perspective view of an example embodiment of a needle thatmay be used in an RF neurotomy procedure.

FIG. 2B is a cut away perspective view of a portion of the needle ofFIG. 2A.

FIG. 2C is a partial cut away and partial cross-sectional view of aportion of another example embodiment of a needle that may be used in anRF neurotomy procedure.

FIG. 2D is a perspective view of another example embodiment of a needlethat may be used in an RF neurotomy procedure.

FIG. 2E is a perspective view of an example embodiment of filamentsformed from a single wire.

FIG. 3A is a detailed view of an example embodiment of a needle tip withfilaments in a fully deployed position.

FIG. 3B is a detailed view of the needle tip of FIG. 3A with filamentsin a retracted position.

FIG. 3C is a detailed view of another example embodiment of a needle tipwith filaments in a deployed position.

FIG. 3D is a detailed view of another example embodiment of a needle tipwith filaments in a fully deployed position.

FIG. 3E is a detailed view of the needle tip of FIG. 3D with filamentsin a retracted position.

FIG. 3F is a cross-sectional view of the needle tip of FIG. 3D withfilaments in a retracted position.

FIG. 3G is a detailed view of yet another example embodiment of a needletip with filaments in a deployed position.

FIGS. 3H and 3I are detailed views of still other example embodiments ofa needle tip with filaments in a deployed position.

FIG. 4 is a schematic diagram of an example embodiment of an RF probeassembly.

FIG. 5 is a proximal-facing end view of an example embodiment of aneedle tip.

FIG. 6 is a side view of an example embodiment of a needle tip.

FIG. 7 is a proximal-facing end view of another example embodiment of aneedle tip.

FIG. 8 is a proximal-facing end view of yet another example embodimentof a needle tip.

FIG. 9 is a proximal-facing end view of still another example embodimentof a needle tip.

FIG. 10 is a side view of another example embodiment of a needle tip.

FIG. 11A is an illustration of an example set of isotherms that may becreated with the needle of FIG. 2A.

FIG. 11B is an illustration of an example lesion that may be createdwith the needle of FIG. 2A.

FIG. 11C is an illustration of an example lesion that may be createdwith a single-filament needle.

FIG. 12 is a perspective view of the needle of FIG. 2A positionedrelative to a lumbar vertebra for performing RF neurotomy.

FIG. 13 is an illustration of a sacrum including target lesion volumesfor performing Sacroiliac Joint (SIJ) RF neurotomy.

FIG. 14 is a perspective view of the needle of FIG. 2A positionedrelative to a thoracic vertebra for performing RF neurotomy.

FIG. 15 is a perspective view of the needle of FIG. 2A positionedrelative to the C2/3 cervical zygapophyseal joint (z-joint) forperforming cervical medial branch RF neurotomy on the third occipitalnerve.

FIG. 16A is a perspective view of an example embodiment of a needle tip.

FIG. 16B is a back elevational view of the needle tip of FIG. 16A.

FIG. 16C is a front elevational view of the needle tip of FIG. 16A.

FIG. 16D is a perspective view of an example embodiment of an elongatemember.

FIG. 16E is a perspective view of the needle tip of FIG. 16A and theelongate member of FIG. 16D.

FIG. 16F is a cross-sectional view of the needle tip and elongate memberof FIG. 16E along the line 16F-16F of FIG. 16E and example embodimentsof a filament and an RF probe.

FIG. 16G is a cross-sectional view of another example embodiment of aneedle tip and elongate member and example embodiments of a filament andan RF probe.

FIG. 17A is an exploded view of components of the deployment mechanismof FIG. 2D.

FIG. 17B is a cross-sectional view of components of the deploymentmechanism of FIG. 2D.

FIG. 17C is a perspective view of an example embodiment of an advancinghub and the wire of FIG. 2E.

FIG. 17D is a cross-sectional view of an example embodiment of a spincollar.

FIG. 17E is a cross-sectional view of an example embodiment of a mainhub, taken along the line 17E-17E of FIG. 17B, in exploded view with anexample embodiment of an elongate member.

FIG. 18A is an axial view of posterior oblique needle entry.

FIG. 18B is a saggital view of posterior oblique needle entry.

DETAILED DESCRIPTION

Although certain embodiments and examples are described below, those ofskill in the art will appreciate that the invention extends beyond thespecifically disclosed embodiments and/or uses and obvious modificationsand equivalents thereof. Thus, it is intended that the scope of theinvention herein disclosed should not be limited by any particularembodiments described below.

In the following description, the invention is set forth in the contextof apparatuses and methods for performing RF ablation. Moreparticularly, the systems and methods may be used to perform RFneurotomy to ablate portions of target nerves. Even more particularly,the systems and methods may be used to perform spinal RF neurotomy toablate portions of target nerves along the spine of a patient to relievepain. For example, embodiments of methods and apparatuses describedherein relate to lumbar RF neurotomy to denervate a facet joint betweenthe L4 and L5 lumbar vertebrae. Denervation may be achieved byapplication of RF energy to a portion of a medial branch nerve to ablateor cauterize a portion of the nerve, thus interrupting the ability ofthe nerve to transmit signals to the central nervous system. In anotherexample, embodiments described herein relate to sacroiliac joint RFneurotomy.

FIG. 1 illustrates an example embodiment of a system 100 for performingRF neurotomy on a patient 101. The patient 101 may be positioned facedown on a table or surface 109 to allow access along the spine of thepatient 101. Other patient orientations are also possible depending onthe procedure. The table 109 may comprise radiolucent materialssubstantially transparent to x-rays, such as carbon fiber.

The system 100 may include an RF generator 102 capable of generating anRF energy signal sufficient to ablate target tissue (e.g.: cause lesionsin targeted volumes; cauterize targeted portions of target nerves). TheRF generator 102 may, for example, be capable of delivering RF energybetween about 1 W and about 200 W and between about 460,000 Hz and about500,000 Hz. A needle 103 capable of conducting (e.g., transmitting ordirecting) RF energy may be interconnected to the RF generator 102 andmay be used to deliver an RF energy signal to a specific site within thepatient 101. In some embodiments in which the needle 103 is a monopolardevice, a return electrode pad 104 may be attached to the patient 101 tocomplete a circuit from the RF generator 102, through the needle 103,through a portion of the patient 101, through the return electrode pad104, and back to the RF generator 102. In some embodiments comprising abipolar arrangement, the needle 103 may comprise at least one supplyelectrode and at least one return electrode to define the circuit.

The RF generator 102 may be operable to control the RF energy emanatingfrom the needle 103 in a closed-loop fashion. For example, the needle103 and/or an RF probe in the needle 103 may include a temperaturemeasurement device, such as a thermocouple, configured to measuretemperature at the target tissue. Data may also be available from the RFgenerator 102, such as power level and/or impedance, which may also beused for closed-loop control of the needle 103. For example, upondetection of a temperature, a parameter (e.g., frequency, wattage,application duration) of the RF generator 102 may be automaticallyadjusted.

FIG. 4 illustrates an example RF probe assembly 400 compatible with theneedle 103. The RF probe assembly 400 includes an RF probe 401 that maybe inserted into a patient (e.g., through the needle 103) and may directRF energy to the target tissue. In some embodiments, the RF probe 401may be in electrical communication with the needle 103 to direct RFenergy to the target tissue, but is not inserted into the patient. TheRF probe 401 may include a thermocouple operable to measure temperatureat a distal end 402 of the RF probe 401. The RF probe assembly 400 mayinclude a connector 403 and a cable 404 configured to connect the RFprobe 401 to an RF generator (e.g., the RF generator 102).

Returning to FIG. 1, the system 100 optionally includes an imagingsystem 105 capable of producing internal images of the patient 101 andthe needle 103, for example to facilitate navigation of the needle 103during a procedure. The system 100 may further include a display devicefor displaying the generated images to a user performing the procedure.In some embodiments, the imaging system 105 comprises a fluoroscopecapable of generating real-time two dimensional images of the needle 103and internal structures of the patient 101. In certain such embodiments,the imaging system includes an X-ray source 106, an X-ray detector 107,and a controller 108 in electrical communication with the X-ray source106 and/or the X-ray detector 107. The X-ray source 106 and X-raydetector 107 may be mounted on a movable structure (e.g., a C-arm), tofacilitate capturing a variety of images of the patient 101 (e.g., atvarious angles or projection views). Other imaging systems 105 are alsopossible (e.g., a computed tomography (CT) scanner).

FIG. 2A illustrates an example embodiment of a needle 103 that may beused in the system 100 for performing RF neurotomy. The needle 103includes a tip 201 that tapers to a point 301 capable of piercing theskin of a patient. In some embodiments, the tip point tapers to a pointsubstantially at the center of the tip 201 (e.g., a “pencil-point” tip).In some embodiments, the tip point tapers to a point substantially atone side of the tip 201 (e.g., a “cutting” or “beveled” or “lancet” or“Quincke” tip). The needle 103 further includes an elongate member 203connected to the tip 201 at a distal end 202 of the needle 103 andconnected to a hub 204 at a proximal end 205 of the needle 103. Theneedle 103 includes a longitudinal axis 223 along the center of theelongate member 203.

FIG. 2D illustrates another example embodiment of a needle 103 that maybe used in the system 100 for performing RF neurotomy. The needle 103includes a tip 211 that tapers to a point 301 capable of piercing theskin of a patient. In some embodiments, the tip point tapers to a pointsubstantially at the center of the tip 211 (e.g., a “pencil-point” tip).In some embodiments, the tip point tapers to a point substantially atone side of the tip 211 (e.g., a “cutting” or “beveled” or “lancet” or“Quincke” tip). The needle 103 further includes an elongate member 203connected to the tip 211 at a distal end 202 of the needle 103 andconnected to a hub 204 at a proximal end 205 of the needle 103. Theneedle 103 includes a longitudinal axis 223 along the center of theelongate member 203.

The needle 103 may include a self-contained mechanical mechanism, in theform of deployable filaments 206 a, 206 b, operable to expand the volumeof effective RF energy delivery as compared to known single-electrode RFprobes. The filaments 206 a, 206 b may be at least partially in theelongate member 203 and may be operable to emerge through one or moreapertures of the needle 103 proximate to the distal end 202 of theneedle 103. In some embodiments, the needle 103 includes a singlefilament or three or more filaments. The filaments 206 a, 206 b allowcontraction/expansion, offsetting, and/or contouring of the effective RFenergy delivery over a selected area of anatomy to adjust lesiongeometry produced using the needle 103 to match a desired target volume(e.g., spherical, hemispherical, planar, spheroid, kidney-shaped,catcher's mitt-shaped, oblong, snowman-shaped, etc.). The filaments 206a, 206 b may be deployable and/or retractable by moving (e.g., rotating)an actuator 216 relative to the hub 204.

As will be further described, the needle 103 may further include a tube207 that includes a lumen 222 therethrough. The lumen 222 may be used totransport fluids to and/or from the target volume. The lumen 222 mayalso accept the RF probe 401 for delivery of RF energy to the targetvolume. The lumen 222 may also accept a dummy or temporary probe, forexample to occlude the fluid port 210 during insertion. In someembodiments, the RF probe 401 is integrated with the needle 103. Incertain such embodiments, the tube 207 need not be present for RF energydelivery, although it may be included to facilitate fluid delivery. Insome embodiments, the filaments 206 a, 206 b include lumens therethroughfor the transportation of fluid to and/or from the target volume. Insome embodiments, the filaments 206 a, 206 b do not include lumenstherethrough (e.g., being solid). The filaments 206 a, 206 b mayfunction as thermocouples.

As RF energy penetrates biological tissue, protein and water moleculesoscillate in response to the RF current and the tissue adjacent to theRF electrode is heated. As the tissue heats and coagulates, thebiophysical properties of the tissue change. These tissue changes limitpenetration of the RF energy beyond a leading edge defined by the shapeand size of an active needle tip. Accordingly, the size of aradiofrequency lesion using conventional single needle technology ispractically limited after achievement of a certain temperature deliveredfor a certain time.

A needle 103 with deployable filaments 206 a, 206 b can overcome thisobstacle and expand the effective area of RF energy delivery byproviding multiple locations (e.g., the tip 201, 211 the filament 206 a,and/or the filament 206 b) from which the RF energy emanates. The use ofmultiple filaments 206 a, 206 b provides additional conduits for RFenergy, creating a multiple electrode RF field effect. The size, shape,and location of a lesion created with the needle 103 may be at leastpartially determined by, for example, the quantity, angle, length,location, and/or orientation of the filaments and RF energy parameterssuch as wattage, frequency, and/or application duration, one or all ofwhich may be beneficially modified to suit a specific anatomicalapplication by changing various aspects of the filaments as discussedbelow.

Where it is desired to create a lesion offset from the centrallongitudinal axis 223, the lesion may be offset in a desired directionfrom the central longitudinal axis 223 by rotationally orienting theneedle 103. The needle 103 may be used to create a lesion offset fromthe central longitudinal axis 223 in a first direction. The filaments206 a, 206 b may be retracted (e.g., after creating a first lesion), theneedle 103 rotated, and the filaments 206 a, 206 b re-deployed to createa lesion offset from the central longitudinal axis 223 in a seconddirection (e.g., to create a second lesion).

FIGS. 3A and 3B are detailed views of an example embodiment of a distalend 202 of a needle 103 that includes a tip 201. The tip 201 may includea sharpened point 301 (e.g., tapering to a point substantially at thecenter of the tip 201, a pencil-point tip) for piercing the skin of apatient and facilitating advancement through tissue. The tip 201 mayinclude a tapered portion 302 that transitions the tip 201 from thepoint 301 to a body portion 303. The body portion 303 is the portion ofthe tip 201 that is proximal to the tapered portion 302. The bodyportion 303 may be cylindrical as illustrated, or may be otherappropriate shapes. The body portion 303 may have a cross-section thatcoincides with (e.g., is coaxial with) the cross section of the elongatemember 203.

FIGS. 3D and 3E are detailed views of another example embodiment of adistal end 202 of a needle 103 that includes a tip 211. The tip 211 mayinclude a sharpened point 301 (e.g., tapering to a point substantiallyat one side of the tip 201, a cutting or beveled or lancet or Quincketip) for piercing the skin of a patient and facilitating advancementthrough tissue. The tip 211 may include a tapered portion 302 thattransitions the tip 211 from the point 301 to a body portion 303. Thebody portion 303 is the portion of the tip 201 that is proximal to thetapered portion 302. The body portion 303 may be cylindrical asillustrated, or may be other appropriate shapes (e.g., as illustrated inFIG. 16A). The body portion 303 may have a cross-section that coincideswith (e.g., is coaxial with) the cross section of the elongate member203. In some embodiments, the tip 211 has a bevel angle between about10° and about 45°, between about 15° and about 35°, between about 20°and about 300 (e.g., about 25°), combinations thereof, and the like.Other bevel angles are also possible. In some embodiments, the point 301has an angle between about 40° and about 120°, between about 70° andabout 90°, between about 75° and about 85° (e.g., about 79°),combinations thereof, and the like. Other angles are also possible.

The tip 201, 211, or a non-insulated portion thereof, may act as an RFenergy delivery element. The tip 201, 211 may comprise (e.g., be madefrom) a conductive material such as, for example, stainless steel (e.g.,300 Series Stainless Steel). The tip 201, 211 may be at least partiallycoated (e.g., with an insulator). The material of the tip 201, 211 andthe material of the optional coating may be selected, for example, toact as an insulator, improve radiopacity, improve and/or alter RF energyconduction, improve lubricity, and/or reduce tissue adhesion.

The tip 201, 211 includes a first filament port or slot 304 a (notvisible in the views of FIGS. 3A, 3B, 3D, and 3E) and a second filamentport or slot 304 b. The geometry of the filament slots 304 a, 304 b maybe selected to allow filaments 206 a, 206 b to be adequately retracted(e.g., such that the filaments 206 a, 206 b are in a cross-sectionalenvelope of the body portion 303 of the tip 201, 211, as shown in FIG.3F) while the needle 103 is inserted into the body, so that thefilaments 206 a, 206 b do not cause any unintended damage to thepatient. Such positioning of the filament slots 304 a, 304 b avoidshaving filament exit features on the tapered portion 302 and thus avoidspotential coring that could be caused by such positioning.

The internal geometry of the filament slots 304 a, 304 b may be designedsuch that the filaments 206 a, 206 b may be easily retracted andadvanced. For example, the internal geometry of the filament slots 304a, 304 b may include a transition region 305 that meets the outersurface of the body portion 303 at an angle of about 30°. The transitionregion 305 may, for example, be curved and/or planar. Advancement offilaments 206 a, 206 b without a pre-set bias (e.g., substantiallystraight) relative to the filament slots 304 a, 304 b can causes thefilaments 206 a, 206 b to be deflected outwardly as the filaments 206 a,206 b move distally along the transition region 305. Depending on thepositioning of the transition region 305 relative to where the filaments206 a, 206 b are confined (e.g., in the needle 103 of FIG. 3A, thefilaments 206 a, 206 b are confined to only longitudinal movement wherethey enter into the elongate member 203) and on the mechanicalproperties of the filaments 206 a, 206 b, various deployment angles ofthe filaments 206 a, 206 b relative to the central longitudinal axis 223may be achieved. Generally, the portions of the filaments 206 a, 206 bthat extend outwardly away from the filament slots 304 a, 304 b may beunrestrained and thus may take any appropriate form. For example, wherethere is no pre-set bias, the portions of the filaments that extendoutwardly away from the filament slots 304 a, 304 b (and therefore fromthe tip) may be substantially straight, such as shown in FIGS. 2A, 3A,3C, 3D, 6, 11A-11C, and 14. For another example, when there is a pre-setbias, the portions of the filaments that extend outwardly away from thefilament slots may take any appropriate shape, such as, for example,curved as shown in FIG. 10.

The radial orientation of the filament slots 304 a, 304 b may beselected such that a center point between the filament slots 304 a, 304b does not coincide (e.g., is not coaxial with) with the centrallongitudinal axis 223. For example, as shown in FIGS. 2A, 3A, 3B, 3D,and 3E, the filament slots 304 a, 304 b may be positioned such that theyare about 120° apart about the circumference of the tip 201, 211. Otherfilament slot configurations may be configured to achieve the filamentplacements discussed below. For example, the filament slots 304 a, 304 bmay be between about 45 and about 180° apart about the circumference ofthe tip 201, 211, between about 90° and about 180° apart about thecircumference of the tip 201, 211, between about 90° and about 150°apart about the circumference of the tip 201, 211, combinations thereof,and the like. Other angles are also possible. These configurations maybe achieved by varying, for example, the quantity of filament slots, theplacement of filament slots about the circumference of the tip 201, 211,and/or the placement of filament slots along the center longitudinalaxis 223 to achieve the filament placements discussed below.

As noted herein, and illustrated in FIGS. 3A and 3B, the needle 103 maycomprise a tube 207 that includes a lumen 222 therethrough. The lumen222 may be employed to accept the RF probe 401 for delivery of RFenergy, for the transport of fluids, and/or for occluding a fluid port210. The tip 201, 211 may include a fluid port 210 that may be in fluidcommunication with the lumen 222 via a channel through the tip 201, 211.In certain embodiments, the lumen 222 is a dual-purpose lumen that canallow injection of fluids and that can receive the distal end 402 of theRF probe 401 to deliver RF energy to the tip 201, 211, the filament 206a, and/or the filament 206 b. In some embodiments, the fluid port 210 islongitudinally spaced from the tip 301 (e.g., by between about 1 mm andabout 3 mm). The fluid port 210 may be centrally located (e.g., asillustrated in FIG. 3D) or it may be located offset from the centerlongitudinal axis 223 (e.g., as shown in FIGS. 2A and 3A). The fluidport 210 may be used to transfer fluid between the region of the tip201, 211 and the proximal end 205 of the needle 103. For example, duringan RF neurotomy procedure, an anesthetic and/or an image enhancing dyemay be introduced into the region of tissue around the tip 201, 211through the fluid port 210. In some embodiments, the fluid port 210 islocated along the tapered portion 302 of the tip 201, 211 (e.g., asillustrated in FIGS. 3A and 3D). In some embodiments, the fluid port 210is located along the body portion 303 of the tip 201, 211.

FIG. 16A is a perspective view of an example embodiment of the needletip 211. In some embodiments, the needle 103 does not comprise a tube207, but the elongate member 203 comprises a lumen 308 therethrough andthe tip 211 comprises a lumen 306 c therethrough. The lumen 308 and thelumen 306 c may be employed to accept the RF probe 401 for delivery ofRF energy, for the transport of fluids, and or for occluding the fluidport 210. In certain embodiments, the lumen 308 and the lumen 306 c aredual-purpose lumens that can allow injection of fluids and that canreceive the distal end 402 of the RF probe 401 to deliver RF energy tothe tip 211, the filament 206 a, and/or the filament 206 b. The filamentlumens 306 a, 306 b may also allow liquid transfer from a proximal endof the needle to the filament ports 304 a, 304 b.

In some embodiments, the filament lumens 306 a, 306 b are sized toinhibit buckling and/or bending of the filaments in the tip 211. In someembodiments, the elongate member 203 may also include filament lumens(e.g., comprising tubes in the elongate member 203). In someembodiments, filament lumens in the elongate member 203 may be formed byan inner member (not shown) extending at least part of the length of theelongate member 203. For example, a transverse cross-section of theinner member may have the same cross-section as the portion of the tip211 illustrated in FIG. 3F, including channels in which the filamentsmay lie and a lumen for passing fluid, an RF probe 401, and/or a dummyprobe.

FIG. 16B is a back elevational view of the needle tip 211 of FIG. 16A.FIG. 16C is a front elevational view of the needle tip 211 of FIG. 16A.The needle tip 211 comprises a filament lumen 306 a in fluidcommunication with and terminating at the filament slot 304 a, afilament lumen 306 b in fluid communication with and terminating at thefilament slot 304 b, and the lumen 306 c. In some embodiments, thelumens 306 a, 306 b are spaced by about 120° along the circumference ofthe tip 211. Other angles are also possible. In some embodiments, thelumen 306 c is spaced from each of the lumens 306 a, 306 b by about 120°along the circumference of the tip 211. Other angles are also possible.Referring again to FIG. 3F, the filament 206 a may be in the filamentlumen 306 a and the filament 206 b may be in the filament lumen 306 b.The lumen 306 c is in fluid communication with the fluid port 210. Insome embodiments, the proximal end of the tip 211 includes a taperedsurface, as shown in FIG. 16A. When filaments 206 a, 206 b are in thefilament lumens 306 a, 306 b, the tapered surface may help to guideinsertion of an RF probe 401 into the lumen 306 c. In some embodiments,the tapered surface has an angle normal to the tip 211 between about 15°and about 75°, between about 30° and about 60°, between about 40° andabout 50° (e.g., about 45°), combinations thereof, and the like. Otherangles are also possible.

FIG. 16D is a perspective view of an example embodiment of an elongatemember 203. The elongate member 203 includes the lumen 308, the filamentslot 304 a, and the filament slot 304 b. In some embodiments, thefilament slots 304 a, 304 b are spaced by about 120° along thecircumference of the elongate member 203. FIG. 16E is a perspective viewof the needle tip 211 of FIG. 16A and the elongate member 203 of FIG.16D. As described herein, the elongate member 203 may be coupled to thetip 211 by adhering with conductive epoxy, welding, soldering,combinations thereof, and the like. A proximal portion of the tip 211can be inserted into the lumen 308 of the elongate member 203. Thefilament slot 304 b of the elongate member 203 is substantially alignedwith the lumen 306 b of the tip 211, allowing the filament 206 b to bedeployed out of the lumen 306 b. Although not illustrated, the filamentslot 304 a of the elongate member 203 is substantially aligned with thelumen 306 a of the tip 211, allowing the filament 206 a to be deployedout of the lumen 306 a. In some embodiments, each of the filament slots304 a, 304 b has a length between about 0.025 inches and about 0.2inches (approx. between about 0.6 mm and about 3 mm), between about 0.05inches and about 0.15 inches (approx. between about 1.3 mm and about 3.8mm), between about 0.075 inches and about 0.125 inches (approx. betweenabout 1.9 mm and about 3.2 mm) (e.g., about 0.105 inches (approx. about2.7 mm)), combinations thereof, and the like. Other lengths are alsopossible. In some embodiments, each of the filament slots 304 a, 304 bhas a width between about 0.01 inches and about 0.4 inches (approx.between about 0.25 mm and about 10 mm), between about 0.02 inches andabout 0.03 inches (approx. between about 0.5 mm and about 0.76 mm),between about 0.015 inches and about 0.025 inches (approx. between about0.38 mm and about 0.64 mm) (e.g., about 0.02 inches (approx. about 0.5mm)), combinations thereof, and the like. Other widths are alsopossible. In some embodiments, the each of the transition regions 305has a length between about 0.02 inches and about 0.2 inches (approx.between about 0.5 mm and about 5 mm), between about 0.05 inches andabout 0.15 inches (approx. between about 1.3 mm and about 3.8 mm),between about 0.075 inches and about 0.125 inches (approx. between about1.9 mm and about 3.2 mm) (e.g., about 0.104 inches (approx. about 2.6mm)), combinations thereof, and the like. Other lengths are alsopossible. In some embodiments in which the transition regions includecurved surfaces, the each of the transition regions 305 has a radius ofcurvature between about 0.01 inches and about 0.4 inches (approx.between about 0.25 mm and about 10 mm), between about 0.15 inches andabout 0.35 inches (approx. between about 3.8 mm and about 8.9 mm),between about 0.2 inches and about 0.3 inches (approx. between about 5mm and about 7.6 mm) (e.g., about 0.25 inches (approx. about 6.4 mm)),combinations thereof, and the like. Other radii of curvature are alsopossible. Certain combinations of dimensions of the transition regions305 and filaments slots 304 a, 304 b described herein may causedeployment of the filaments 206 a, 206 b at desired angles (e.g., about30°).

The lumen 308 is not visible in FIG. 16E because the elongate member 203covers the lumen 308. Covering the lumen 308 causes fluid inserted intothe lumen 308 to exit the fluid port 210, and possibly the filamentslots 304 a, 304 b. In some embodiments, for example as illustrated inFIGS. 3A and 3B, the elongate member 203 may also include a slotproximate to the tube 207. In certain such embodiments, the tube 207 mayextend distal to the slot and substantially all fluid inserted into thelumen 222 exits the fluid port 210.

In the embodiment illustrated in FIG. 16E, the body portion 303 of thetip 211 and the elongate member 203, excluding the sleeve 307, havesubstantially equal diameters, for example to provide a smoothtransition between the tip 211 and the elongate member 203. In someembodiments, the elongate member 203 has an inner diameter between about0.01 inches and about 0.04 inches (approx. between about 0.25 mm andabout 1 mm), between about 0.015 inches and about 0.035 inches (approx.between about 0.38 mm and about 0.89 mm), between about 0.02 inches andabout 0.03 inches (approx. between about 0.5 mm and about 0.76 mm)(e.g., about 0.025 inches (approx. about 0.64 mm)), combinationsthereof, and the like. Other diameters are also possible. In someembodiments, the elongate member 203 has an outer diameter between about0.01 inches and about 0.05 inches (approx. between about 0.25 mm andabout 1.3 mm), between about 0.02 inches and about 0.04 inches (approx.between about 0.5 mm and about 1 mm), between about 0.025 inches andabout 0.035 inches (approx. between about 0.64 mm and about 0.89 mm)(e.g., about 0.029 inches (approx. about 0.74 mm)), combinationsthereof, and the like. Other diameters are also possible. In someembodiments, the proximal portion of the tip has an outer diameterbetween about 0.01 inches and about 0.04 inches (approx. between about0.25 mm and about 1 mm), between about 0.015 inches and about 0.035inches (approx. between about 0.38 mm and about 0.89 mm), between about0.02 inches and about 0.03 inches (approx. between about 0.5 mm andabout 0.76 mm) (e.g., about 0.025 inches (approx. about 0.64 mm)),combinations thereof, and the like. Other diameters are also possible.In some embodiments, the tip 211 has an outer diameter between about0.01 inches and about 0.05 inches (approx. between about 0.25 mm andabout 1.3 mm), between about 0.02 inches and about 0.04 inches (approx.between about 0.5 mm and about 1 mm), between about 0.025 inches andabout 0.035 inches (approx. between about 0.64 mm and about 0.89 mm)(e.g., about 0.029 inches (approx. about 0.74 mm)), combinationsthereof, and the like. Other diameters are also possible.

FIG. 16F is a cross-sectional view of the needle tip 211 and theelongate member 203 along the line 16F-16F of FIG. 16E. FIG. 16F alsoillustrates an example embodiment of a filament 206 a in the lumen 308and the lumen 306 a, then exiting via the filament slot 304 a, and an RFprobe 401 in the lumen 308. In some embodiments, the elongate member 203and the tip each 211 comprise (e.g., are each made from) a conductivematerial (e.g., 300 Series Stainless Steel), and can conduct electricalsignals from the RF probe 401 to the tip 211 and the filaments 206 a,206 b (e.g., due to physical contact of conductive components) to form amonopolar electrode. In some embodiments, the RF probe 401, thefilaments 206 a, 206 b, the tip 211, and/or the elongate member 203 mayinclude features configured to increase physical contact between thecomponents. The cross-sectional view shows the lumen 308 in fluidcommunication with the lumen 306 c and the fluid port 210.

FIG. 16G is another cross-sectional view of an example embodiment of aneedle tip 211 and the elongate member 203 along a line similar to theline 16F-16F in FIG. 16E. The tip 211 in FIG. 16G does not include afluid port 210, but fluid can permeate out of the filament slots 304 a,304 b because the filament slots are in fluid communication with thelumen 308. In some embodiments, the tip 211 includes a lumen 306 c, forexample to assure placement of or contact with the probe 401 (e.g., asillustrated in FIG. 16G). In some embodiments, the tip 211 does notinclude a lumen 306 c, for example to reduce manufacturing costs if thelumen 306 c is cut from a solid tip stem.

As may be appreciated, the channel through the tip 201, 211 may be sizedto accommodate a tip of the RF probe 401 that may be inserted into theneedle 103. The channel may be sized such that RF energy from theinserted RF probe 401 is satisfactorily communicated from the RF probe401 to the tip 201, 211, the filament 206 a, and/or the filament 206 b.

FIGS. 3C and 3G are each a detailed view of the distal end 310 of aneedle 309 that is an alternate embodiment of the needle 103. The distalend 310 includes a tip 311, 321 that may include a sharpened point 312for piercing the skin of a patient and facilitating advancement throughtissue. The tip 311, 321 may include a tapered portion 313 thattransitions the tip 311, 321 from the point 312 to a first body portion314. The first body portion 314 may be connected to a second bodyportion 315 at an angle 316. In some embodiments, the angle 316 is about15°. Other angles 316 are also possible. For example, the angle 316 maybe between about 5° and about 90°, between about 10° and about 60°,between about 10° and about 45°, between about 10° and about 20°,combinations thereof, and the like. Other angles are also possible. Thesecond body portion 315 may be aligned with an elongate member 317. Theelongate member 317 may be similarly configured as the elongate member203 of FIGS. 3A, 3B, 3C, and 3D. The angle 316 between the first bodyportion 314 and the second body portion 315 may aid the user innavigating the needle 309 to a desired position. For example, byrotating the needle 309 such that the first body portion 314 is pointingin a desired direction, subsequent advancement of the needle 309 mayresult in the needle 309 following a non-straight path biased toward thedesired direction.

The first and second body portions 314, 315 may be cylindrical asillustrated, or they may be of any other appropriate shape. The firstand second body portions 314, 315 may have cross-sections that coincidewith (e.g., is coaxial with) the cross section of the elongate member317.

The tip 311, 321, or a non-insulated portion thereof, may act as an RFenergy delivery element. The tip 311, 321 may comprise (e.g., be madefrom) a conductive material such as, for example, stainless steel (e.g.,300 Series Stainless Steel). The tip 311, 321 may be coated (e.g., withan insulator). The material of the tip 311, 321 and the material of theoptional coating may be selected, for example, to act as an insulator,improve radiopacity, improve and/or alter RF energy conduction, improvelubricity, and/or reduce tissue adhesion.

The filaments 319 a, 319 b may also act as RF energy delivery elements.The filaments 319 a, 319 b may be constructed in a manner similar to asdescribed with respect to the filaments 206 a, 206 b.

The tip 311 of FIG. 3C includes a filament slot 318 a and a filamentslot 318 b. The geometry of the filament slots 318 a, 318 b may beselected to allow filaments 319 a, 319 b to be adequately retracted(e.g., such that they are in a cross-sectional envelope of the secondbody portion 315) while the needle 309 is inserted into the body, sothat the filaments 319 a, 319 b do not cause any unintended damage tothe patient (e.g., by being along the second body portion 315). Suchpositioning of the filament slots 318 a, 318 b may avoid having filamentexit features on the tapered portion 313 and on the first body portion314, which may avoid potential coring. The internal geometry of thefilament slots 318 a, 318 b may include a transition region that meetsthe outer surface of the second body portion 315 at an angle, andadvancement of filaments 319 a, 319 b without a pre-set bias (e.g.,substantially straight) relative to the filament slots 318 a, 318 b cancauses the filaments 319 a, 319 b to be deflected outwardly as thefilaments 319 a, 319 b move distally along the transition region.

The configuration and orientation of the filament slots 318 a, 318 b maybe selected such that deployed filaments 319 a, 319 b may achieve thepositioning illustrated in FIG. 3C. In FIG. 3C, the filaments 319 a, 319b are generally positioned in a plane that is perpendicular to a planethat includes the angle 316 between the first and second body portions314, 315. As illustrated, the filaments 319 a, 319 b may be positionedsuch that they extend at an angle (e.g., about 15°, between about 10°and about 90°, between about 10° and about 60°, between about 10° andabout 45°, between about 10° and about 20°, combinations thereof, andthe like) relative to the plane that includes the angle 316. Otherangles are also possible. Other filament slot 318 a, 318 bconfigurations may be configured to achieve other desired filament 319a, 319 b placements. These configurations may be achieved, for example,by varying the quantity of filament slots and filaments, the placementof filament slots about the circumference of the tip 311, the angle atwhich the filaments extend away from the first and second body portions314, 315, and/or the placement of filament slots along the first andsecond body portions 314, 315.

FIG. 3G illustrates an example embodiment of a tip 321 that includes afilament slot 318 a and a filament slot 318 b along the first bodyportion 314. The geometry of the filament slots 318 a, 318 b may beselected to allow filaments 319 a, 319 b to be adequately retracted(e.g., such that they are in a cross-sectional envelope of the secondbody portion 315) while the needle 309 is inserted into the body, sothat the filaments 319 a, 319 b do not cause any unintended damage tothe patient. Positioning of the filament slots 318 a, 318 b along thefirst body portion 314 may potentially cause coring, so the filaments319 a, 319 b may be configured to substantially occlude the filamentslots 318 a, 318 b, which may avoid potential coring. The internalgeometry of the filament slots 318 a, 319 b may lack a transition regionand, due to being positioned on the first body portion 314, advancementof the filaments 319 a, 319 b without a pre-set bias (e.g.,substantially straight) can cause the filaments 319 a, 319 b to continueto advance substantially straight (e.g., along the longitudinal axis ofthe elongate member 317 and/or the second body portion 315) as thefilaments move distally out of the filament slots 318 a, 318 b. Althoughnot illustrated, placement of filament slots along the tapered portion313 is also possible (e.g., the filaments continuing to advance alongthe longitudinal axis of the first body portion 314). Although notillustrated, the embodiments depicted in FIGS. 3A and 3D may be adaptedso the filaments 206 a, 206 b exit along the tapered portion 302.

The needle 309 may comprise a tube that includes a lumen therethrough,for example as described herein with respect to FIGS. 3A, 3B, 3D, and3E. The lumen may be employed to accept an RF probe for delivery of RFenergy and/or for the transport of fluids. In this regard, the tip 311may further include a fluid port 320 that may be in fluid communicationvia a channel through the tip 311 with the lumen. The fluid port 320 maybe used to transfer fluid between the region of the tip 311 and aproximal end of the needle 309.

In the deployed position as shown in FIG. 3C, the distal ends of thefilaments 319 a, 319 b are disposed away from the point 312. In thedeployed position as shown in FIG. 3G, the distal ends of the filaments319 a, 319 b are disposed away from the point 312. In a retractedposition (not shown, but similar to as shown in FIGS. 3B and 3E), thedistal ends of the filaments 319 a, 319 b are entirely within an outerperimeter (e.g., circumference where the second body portion 315 of thetip 311, 321 is round) of the tip 311, 321. In the deployed position,the filaments 319 a, 319 b act as broadcast antennae for an RF probeinserted into the needle 309. The tip 311 or 321, the filament 319 a,and/or the filament 319 b may form a monopolar electrode for applicationof RF energy to the target volume. The filaments 319 a, 319 b may allowthe RF energy from the RF probe to be dispersed over a larger volumethan would be possible with the tip 311, 321 alone.

In general, any or all of the herein variables may be incorporated intoa particular embodiment of a needle to yield a needle capable ofproducing a lesion with a particular size, position and shape relativeto the tip of the needle. Such custom sizes, positions and shapes may bedesigned for specific procedures. For example, a particular lesion size,position and shape may be selected to enable a user to navigate theneedle to a particular landmark (e.g., proximate to or touching a bonevisible using fluoroscopy) and then orient the needle such that deployedfilaments will be operable to produce a lesion at a particular locationrelative to the landmark. By navigating to a particular internallandmark, as opposed to attempting to visualize a relative position of aneedle offset from a landmark, a more accurate and/or consistentpositioning of the needle may be achieved. In this regard, the skilllevel required to accurately position the needle for a particularprocedure may be reduced.

The lesion shapes achievable through selection of the herein variablesmay include, for example, generally spherical, oblong, conical, andpyramidal shapes. The orientation relative to, and the amount of offsetfrom, the tip of such shapes may be selectable. In an embodiment, thetips of the deployed filaments may be positioned distally relative tothe point of the tip to provide for a facile positioning of the lesionrelative to the tip. Such capability may allow for the needle to beinserted directly toward a target volume. In other embodiments, the tipsof the deployed filaments may be positioned at the same axial positionalong the central longitudinal axis as the point of the tip or the tipsof the deployed filaments may be positioned proximally relative to thepoint of the tip. In other embodiments, some filament endpoints may belocated distal to the point of the tip while others are proximal to thepoint of the tip.

The elongate member 203 may be in the form of a hollow tube (e.g.,sheath, cannula) interconnecting the tip 201, 211 with the hub 204. Theelongate member 203 may be configured with adequate strength to allowthe needle 103 to pierce a patient's skin and advance to a target areathrough various tissue types, including, for example, fat and muscletissue. The elongate member 203 may also be capable of resisting kinkingas it is advanced. In some embodiments, the elongate member 203comprises a rod with a plurality of lumens along its length toaccommodate the filaments 206 a, 206 b, the RF probe 401, and/or a fluidpassage.

The elongate member 203 houses portions of the filaments 206 a, 206 band the tube 207, and allows for relative movement of the filaments 206a, 206 b. The elongate member 203 may be of any appropriate size andinternal configuration to allow insertion into a patient and to housecomponentry therein. In some embodiments, the elongate member 203 is a16 gauge round tube or smaller. For example, the elongate member 203 maybe 18 gauge or 20 gauge. In some embodiments, the elongate member 203has a maximum cross-sectional dimension of about 1.7 mm. In someembodiments, the elongate member 203 has a maximum cross-sectionaldimension of about 1 mm. The elongate member 203 may have a lengthselected for performing a specific spinal RF neurotomy procedure on aparticular patient. In some embodiments, the elongate member 203 has alength of about 10 cm.

In certain embodiments, the elongate member 203 comprises (e.g., isconstructed from) an insulative material to reduce (e.g., eliminate) theamount of RF energy emitted along the length of the elongate member 203when the RF probe 401 is disposed therein. For example, the elongatemember 203 may comprise (e.g., be constructed from) polymeric, ceramic,and/or other insulative material. In certain embodiments, the elongatemember 203 includes an insulating coating or sleeve 307 (FIGS. 2D and16D). In some embodiments, the elongate member is insulated (e.g.,constructed from insulative material and/or having an insulating coating307) except for a distal part having a length between about 5 mm andabout 10 mm. FIG. 3H illustrates an example embodiment of a needle 309comprising an insulating coating 330 covering a proximal portion of thetip 321 and coatings 332 a, 332 b covering a proximal portion of thefilaments 319 a, 319 b. The coating 330 insulates, inter alia, the bentarea between the first body portion 314 and the second body portion 315of the tip 321.

In some embodiments, the elongate member is insulated (e.g., constructedfrom insulative material and/or having an insulating coating) except fora proximal part. FIG. 3I illustrates an example embodiment of a needle309 comprising an insulating coating 330 covering a distal portion ofthe tip 321 and coatings 332 a, 332 b covering a distal portion of thefilaments 319 a, 319 b. In some embodiments in which the distal portionof the tip 321 is, the needle 309 may create a kidney or catcher's mittshaped lesion, which may be useful, for example, for ablating tissuewhere the active tip is pressed against the wall of a structure with thedevice staying in the lumen of a structure. For example, when ablatingendocardial lesions in which the device accesses the target through acardiac chamber, insulating the distal portion of the tip 321, whichstays in the chamber, can make the biophysics of the lesion (e.g.,impedance, power, heat) more precise because the insulated distalportion of the tip 321 that is surrounded by blood in the chamber willnot be part of the field.

FIGS. 3H and 3I illustrate example embodiments of insulation of parts ofthe tip 321 and the filaments 319 a, 319 b illustrated in FIG. 3G. Partsof components of the distal ends of other needle tips described hereinmay also be insulated (e.g., those illustrated in FIGS. 3A, 3C, and 3D).In some embodiments, only parts of the tip 321, and not parts of thefilaments 319 a, 319 b, are insulated. In some embodiments, only partsof the filaments 319 a, 319 b, and not parts of the tip 321, areinsulated. In some embodiments, a distal portion of the tip 321 isinsulated (e.g., as illustrated in FIG. 3) and proximal portions of thefilaments 319 a, 319 b are insulated (e.g., as illustrated in FIG. 3H).In some embodiments, a distal portion of the filaments 319 a, 319 b areinsulated (e.g., as illustrated in FIG. 3I) and a proximal portion ofthe tip 321 is insulated (e.g., as illustrated in FIG. 3H). In someembodiments, the insulative coating or sleeve 330, 332 a, 332 b may beadjustable. For example, one or all of the sleeves 330, 332 a, 332 b maybe advanced or retracted relative to the tip 321, the filament 319 a,and the filament 319 b, respectively, to increase or decrease the amountof exposed conductive area.

The elongate member 203 may include a coating that may improveradiopacity to aid in visualization of the position of the needle 103using fluoroscopy. The elongate member 203 may include a lubriciouscoating to improve its ability to be inserted and positioned in thepatient and/or to reduce tissue adhesion. The elongate member 203 mayinclude markers 224 along its length to assist in determining the depthto which the needle 103 has entered into the anatomy. The markers 224may be radiopaque so that they may be viewed under fluoroscopy. A collar(not shown) may be disposed about the elongate member 203 to assist inplacement of the tip 201, 211 of the needle 103. For example, the tip201, 211 may be positioned in a first position, the collar may then beplaced against the patient's skin, and then the needle 103 may beadvanced and/or withdrawn a certain distance. Such a distance may beindicated, for example, by the distance between the collar and apatient's skin or other anatomy.

The elongate member 203 may be fixedly interconnected to the tip 201,211 and the hub 204 in any appropriate manner. For example, the tip 201,211 may be press fit into the elongate member 203 and the elongatemember 203 may be press fit into the hub 204. Other example methods ofattachment include adhesive bonding and welding. In some embodiments,the elongate member 203 and the tip 201, 211 are a single unitarystructure. The elongate member 203 may be steerable and incorporatecontrolling mechanisms allowing the elongate member 203 to be deflectedor steered after insertion into the anatomy.

The tube 207 containing the lumen 222 may comprise (e.g., be constructedfrom) any appropriate material. For example, the tube 207 comprise aconductive material, such as stainless steel (e.g., 300 Series StainlessSteel), such that when the RF probe 401 is inserted in the tube 207, theRF energy emitted by the RF probe 401 may be conducted through the tube207 and into and through the tip 201, 211, the filament 206 a, and/orthe filament 206 b. The tube 207 may be interconnected to the tip 201,211 such that the lumen 222 is in sealed, fluid communication with thechannel through the tip 201, 211. This may be accomplished by a pressfit, weld, or any other appropriate method.

As noted, the lumen 222 may be in fluid communication with the tip 201,211 at the distal end 202. A proximal end of the lumen 222 may bedisposed at the proximal end 205 of the needle 103. In this regard, thelumen 222 may extend from the distal end 202 to the proximal end 205,with the only access being at the distal and proximal ends 202, 205. Insome embodiments, the lumen 222 is the only lumen of the needle 103disposed along the elongate member 203.

The RF probe 401 inserted into the lumen 222 may be positioned such thatan end of the RF probe 401 is proximate to the tip 201, 211. Forexample, the RF probe 401 may be positioned such that the distal end 402of the RF probe 401 is in the lumen 222 near the tip 201, 211 or in thechannel through the tip 201, 211. RF energy transmitted through the RFprobe 401 may then be conducted by the tip 201, 211, the filament 206 a,and/or the filament 206 b. The size of the lumen 222 may be selected toaccommodate a particular size of RF probe 401. For example, the lumen222 may be configured to accommodate at least a 22 gauge RF probe 401,at least a 21 gauge RF probe 401, or a larger or smaller RF probe 401.For another example, the lumen 222 may have a maximum cross-sectionaldimension of less than about 0.85 mm.

The proximal end of the tube 207 may be operable to receive the RF probe401. The proximal end of the tube 207 and the actuator 216 may beconfigured to accept a connector, such as a Luer fitting, such that afluid source may be connected to the tube 207 (e.g., to deliver fluidthrough the lumen 222 and out the fluid port 210).

The needle 103 includes two filaments 206 a, 206 b in and along elongatemember 203. Distal ends of the filaments 206 a, 206 b are proximate tothe tip 201, 211, and proximal ends of the filaments 206 a, 206 b arefixed to a filament hub 221 discussed below. The filaments 206 a, 206 bare movable along the central longitudinal axis 223 between a fullydeployed position as illustrated in FIGS. 3A, 3C, 3D, and 3F and aretracted position illustrated in FIGS. 3B and 3E. Moving the filaments206 a, 206 b distally from the retracted position moves the filaments206 a, 206 b toward the fully deployed position, while moving thefilaments 206 a, 206 b proximally from the deployed position moves thefilaments 206 a, 206 b toward the retracted position. The filaments 206a, 206 b may be deployed in intermediate positions between the fullydeployed positions and the retracted positions. For example, a mechanismfor advancement and/or retraction of the filaments 206 a, 206 b mayinclude detents indicating partial deployment and/or retraction and astop indicating full deployment and/or retraction.

In the fully deployed position, the distal ends of the filaments 206 a,206 b, 319 a, 319 b are disposed away from the tip 201, 211, 311, 321.In the retracted position, the distal ends of the filaments 206 a, 206b, 319 a, 319 b are entirely within an outer perimeter (e.g.,circumference where the body portion 303 of the tip 201, 211, 311, 321is round) of the tip 201, 211, 311, 321. In the deployed position, thefilaments 206 a, 206 b, 319 a, 319 b can act as broadcast antennae forthe RF probe 401 (e.g., RF energy passes from the RF probe 401 to thetip 201, 211, 311, 321 and to the filaments 206 a, 206 b, 319 a, 319 b,and into a target volume within a patient). In this regard, together,the RF probe 401 inserted into the lumen 222, the tip 201, 211, 311,321, and the filaments 206 a, 206 b, 319 a, 319 b, may form a monopolarelectrode for application of RF energy to the target volume. Thefilaments 206 a, 206 b, 319 a, 319 b allow the RF energy from the RFprobe 401 to be dispersed over a larger volume than would be possiblewith the tip 201, 211, 311, 321 alone.

The filaments 206 a, 206 b, 319 a, 319 b may be constructed from amaterial operable to conduct RF energy, e.g., a metal such as stainlesssteel (e.g., 303 Stainless Steel), Nitinol, or shape memory alloy. Thefilaments 206 a, 206 b may be coated, for example to enhance and/orinhibit their ability to conduct RF energy. The filaments 206 a, 206 bmay include a lubricious coating to aid in insertion and/or reducetissue adhesion.

FIG. 2E illustrates an embodiment in which the filaments 206 a, 206 bare formed from a single wire 206 that is bent at the proximal end. Thedistal ends of the filaments 206 a, 206 b are shown as bent, which canbe the result of deflection upon exit from a tip 201, 211, shape memory,combinations thereof, and the like. Forming the filaments 206 a, 206 bfrom a single wire 206 may provide advantages such as, for example,coherent activation of the filaments 206 a, 206 b, simultaneousdeployment of the filaments 206 a, 206 b, and/or simultaneous retractionof the filaments 206 a, 206 b. It will be appreciated that the wire 206may be a single wire or a plurality of wire segments joined together(e.g., via adhering with conductive epoxy, welding, soldering,combinations thereof, and the like). Other filaments described hereinmay also be coupled or bent at the proximal end. The filaments 206 a,206 b illustrated in FIG. 2E are substantially parallel, and taperoutwards before being bent at the proximal end. In some embodiments, thefilaments 206 a, 206 b are substantially parallel and do not taper outbefore being bent at the proximal end. In certain such embodiments, theproximal end of the wire 206 is a semi-circle, for example having aradius between about 0.03 inches and about 0.07 inches (approx. betweenabout 0.76 mm and about 1.8 mm), between about 0.04 inches and about0.06 inches (approx. between about 1 mm and about 1.5 mm), between about0.05 inches and about 0.055 inches (approx. between about 1.3 mm andabout 1.4 mm) (e.g., about 0.052 inches (approx. about 1.32 mm)),combinations thereof, and the like. In some embodiments, the filaments206 a, 206 b are parallel and spaced by a distance between about 0.025inches and about 0.125 inches (approx. between about 0.64 mm and about3.2 mm), between about 0.05 inches and about 0.1 inches (approx. betweenabout 1.3 mm and about 2.5 mm) (e.g., about 0.075 inches (approx. about1.9 mm)), combinations thereof, and the like. In some embodiments, thefilaments 206 a, 206 b in the elongate member 203 may be braided,wrapped, or twisted together. Such embodiments may increase columnstrength, providing resistance to buckling and/or bending in theelongate member 203. In some embodiments, the wire 206 has a diameterbetween about 0.0025 inches and about 0.04 inches (approx. between about0.06 mm and about 1 mm), between about 0.005 inches and about 0.025inches (approx. between about 0.13 mm and about 0.64 mm), between about0.01 inches and about 0.02 inches (approx. between about 0.25 mm andabout 0.5 mm) (e.g., about 0.014 inches (approx. about 0.36 mm)),combinations thereof, and the like. Other diameters are also possible.In some embodiments, the filaments 206 a, 206 b each have a diameterbetween about 0.0025 inches and about 0.04 inches (approx. between about0.06 mm and about 1 mm), between about 0.005 inches and about 0.025inches (approx. between about 0.13 mm and about 0.64 mm), between about0.01 inches and about 0.02 inches (approx. between about 0.25 mm andabout 0.5 mm) (e.g., about 0.014 inches (approx. about 0.36 mm)),combinations thereof, and the like. Other diameters are also possible.In some embodiments, the filaments 206 a, 206 have different diameters(e.g., by being formed from different wires, by being formed fromportions of wires with different diameters that are coupled to form thewire 206, etc.).

The distal ends of the filaments may be shaped (e.g., pointed) toimprove their ability to move through tissue. For example, the tips ofthe filaments 206 a, 206 b in FIG. 3A have an outward-facing bevel. Insome embodiments, the bevel is at an angle between about 15° and about45°, between about 20° and about 40°, between about 25° and about 35°(e.g., about 30°), combinations thereof, and the like. In embodiments inwhich the filaments 206 a, 206 b each have a diameter of about 0.014inches (approx. about 0.36 mm) and a bevel of about 30°, the length ofthe bevel is about 0.024 inches (approx. about 0.61 mm). The tips of thefilaments 206 a, 206 b may have the same shape (e.g., beveled) ordifferent shapes. For another example, the tips of the filaments 206 a,206 b in FIG. 3D have an inward-facing bevel. In certain embodiments,bevels (e.g., inward-facing bevels) can help to induce splay between thetips of the filaments 206 a, 206 b (e.g., splay of between about 15° andabout 20°) by tracking to one side (e.g., away from the beveled side)upon deployment, which can improve placement of the filaments 206 a, 206b. For yet another example, the tips of the filaments 319 a, 319 b inFIG. 3G have a pencil-point. In certain embodiments, a pencil-point tipcan help to reduce splay between the tips of the filaments 206 a, 206 bby substantially straight tracking deployment, which can improveplacement of the filaments 206 a, 206 b. In some embodiments, thefilaments 206 a, 206 b comprise materials with different tensilestrength and/or rigidity, and the filaments 206 a, 206 b, which canaffect their ability to flex due to contact with tissue and thus theamount of splay, if any. In certain embodiments in which the filaments206 a, 206 b comprise a shape memory material, the deflection to anunconfined state may work with or against the shapes of the tips. Insome embodiments, certain filament tips may help to occlude filamentsslots, improve interaction with a transition region, etc. Althoughcertain combinations of filament tips are illustrated with respect tocertain embodiments herein, the various shapes of the filament tipsdescribed herein and otherwise may be selected for any of theseembodiments (e.g., the filaments 206 a, 206 b of FIG. 3A may haveinwardly-facing bevels or pencil-point tips, the filaments 206 a, 206 bof FIG. 3D may have outwardly-facing bevels or pencil-point tips, thefilaments 319 a, 319 b of FIG. 3C may have inwardly-facing bevels orpencil-point tips, the filaments 319 a, 319 b of FIG. 3G may haveinwardly-facing bevels or outwardly-facing bevels, etc.).

The positioning of the filaments 206 a, 206 b of the embodimentsillustrated in FIGS. 3A and 3D will now be described in relation to FIG.5. FIG. 5 is an end view of the tip 201 and deployed filaments 206 a,206 b of the embodiment illustrated in FIGS. 2A and 3A. The filaments206 a, 206 b are positioned at a filament angle 503 of about 120° apartfrom each other about the central longitudinal axis 223. This coincideswith the positions of the filament slots 304 a, 304 b discussed hereinsince the filaments 206 a, 206 b emerge from the filament slots 304 a,304 b. Other filament angles 503 are also possible. For example, thefilament angle 503 may be between about 90° and about 180°, betweenabout 90° and about 150°, between about 100° and about 140°, betweenabout 110° and about 130°, combinations thereof, and the like. Afilament-free angle 504 of about 240° is defined as the largest angleabout the circumference of the tip 201, 211 that is free of filaments.In an embodiment consisting of two filaments 206 a, 206 b, the filamentangle 503 may be less than 180° and the filament-free angle 504 may becorrespondingly greater than 180° (e.g., greater than 200° or greaterthan 240°).

In FIG. 5, the central longitudinal axis 223 is perpendicular to theplane of the illustration. A midpoint 502 is defined between distal ends501 a, 501 b of the filaments 206 a, 206 b, respectively. The midpoint502 is offset from the central longitudinal axis 223. For example, insome embodiments, the midpoint 502 is offset from the centrallongitudinal axis 223 by about 2 mm. Other offset values are alsopossible. For example, the offset may be between about 0.5 mm and about5 mm, between about 1 mm and about 4 mm, between about 1 mm and about 3mm, greater than about 0.5 mm, less than about 5 mm, combinationsthereof, and the like. When RF energy is transmitted from the tip 201and both of the filaments 206 a, 206 b, the RF energy will betransmitted asymmetrically with respect to the central longitudinal axis223 the cause the RF energy will be emitted from the tip 201 and thefilaments 206 a, 206 b. As oriented in FIG. 5, the energy will be biasedin an upward direction in the direction from the point 301 toward themidpoint 502. Thus, when RF energy is transmitted during an RF neurotomyprocedure, a lesion will be created that is correspondingly offset fromthe central longitudinal axis 223 in the direction from the point 301toward the midpoint 502.

Referring again to the asymmetric nature of the lesion, the lesion maybe substantially a three-dimensional polygon (e.g., with rounded edges)of known dimensions and volume that is offset from the central cannulain a known and predictable way. Different embodiments may have differentthree-dimensional polygonal structures adapted to the intended ablationtarget. By contrast, needles without deployable filaments may be used tocreate asymmetric planar lesions by varying needle insertion during theablation procedure, and may require substantial ablation volume overlap.

FIG. 6 is a side view of the tip 201 and the filaments 206 a, 206 b,oriented such that the deployed filament 206 b is entirely within theplane of the figure. The filaments 206 a, 206 b extend from the tip 201at a common distance, or location, along the central longitudinal axis223. In some embodiments, the filaments 206 a, 206 b may extenddifferent distances. The filament 206 b is deflected radially outwardlyfrom the central longitudinal axis 223. The filament 206 b emerges fromthe tip 201 at an angle 601 of about 30° from the central longitudinalaxis 223, which is parallel to the longitudinal axis of the elongatemember 203. The angle 601 may vary, for example, based at leastpartially on positioning of a transition region 305, mechanicalproperties of the filament 206 b (e.g., shape-memory properties or lackthereof), and the like. In some embodiments, the angle 601 is betweenabout 5° and about 85°, between about 10° and about 60°, between about20° and about 40°, greater than about 5°, less than about 85°,combinations thereof, and the like. In some embodiments, the angle 601is related to the angle 503. For example, the angle 601 may be afraction of the angle 503, such as about ¼. In some embodiments, theangle 601 is unrelated to the angle 503, for example both beingindependently chosen to produce a certain lesion size or shape. In someembodiments, the distal tips 501 a, 501 b are positioned distally beyondthe point 301 by a distance 602, are disposed at a distance 603 from thecentral longitudinal axis 223, and/or are disposed at a distance 604from each other. In some embodiments, the distance 602 is about 3.5 mm,the distance 603 is about 3 mm, and/or the distance 604 is about 4.5 mm.Other distances are also possible. For example, in some embodiments, thedistance 602 is between about 0.5 mm and about 6 mm, between about 1 mmand about 5 mm, between about 3 mm and about 4 mm, combinations thereof,and the like. Other distances are also possible. For another example, insome embodiments, the distance 603 is between about 0.5 mm and about 6mm, between about 1 mm and about 5 mm, between about 2 mm and about 4mm, combinations thereof, and the like. Other distances are alsopossible. For yet another example, in some embodiments, the distance 604is between about 2 mm and about 7 mm, between about 3 mm and about 6 mm,between about 4 mm and about 5 mm, combinations thereof, and the like.Other distances are also possible.

The angles described herein (e.g., the angles 503, 601) may be measuredwith respect to a needle 103 in a deployed state outside of a patient'sbody, and that the angles may when the needle is inside a patient'sbody, for example based at least in part on splay of filaments due tobeveling.

The tip 211 and deployed filaments 206 a, 206 b of the embodimentillustrated in FIG. 3D may also have a filament angle 503, afilament-free angle 504, a midpoint 502, an angle 601, distances 602,603, 604, and other features described herein, for example with respectto FIGS. 5 and 6. In some embodiments, the portion of the lesion basedat least partially on RF energy emitted by the tip 211, and thus theshape of the lesion, may vary based on the position of the point 301(e.g., in FIG. 3d , the point 301 is on the side of the tip 211 thatcomprises the filaments 206 a, 206 b).

The configuration of the filaments 206 a, 206 b illustrated in FIGS. 2A,3A, 3D, 5, and 6 may be operable to produce lesions that are radiallyoffset from the central longitudinal axis 223 and distally offset fromthe point 301 as compared to a lesion created by the tip 201, 211without the filaments or a lesion created with the needle 103 with thefilaments 206 a, 206 b in the retracted position.

Variations in the relative shapes, positions, and sizes of lesionscreated with the needle may be achieved by repositioning the filaments.For example, as noted herein, the lesion produced by the needle will bein different positions depending on whether the filaments are in thedeployed or retracted positions. Lesions having intermediate shapes,positions, and/or sizes may be achieved by positioning the filaments inintermediate positions between the fully deployed (e.g., as illustratedin FIGS. 3A, 3C, 3D, and 3G) and fully retracted positions (e.g., asillustrated in FIGS. 3B and 3E). As noted herein, the needle withdeployed filaments is operable to produce larger lesion volumes than theneedle with retracted filaments. For example, the needle with fullydeployed filaments may be operable to produce lesion volumes of about500 mm³. Other lesion volumes are also possible. For example, the needlewith fully deployed filaments may be operable to produce lesion volumesbetween about 100 mm³ and about 2,000 mm³, between about 200 mm³ andabout 1,000 mm³, between about 250 mm³ and about 750 mm³, between about400 mm³ and about 600 mm³, combinations thereof, and the like.

Further variation in the shape, position, and/or size of lesions createdby needles with deployable filaments may be achieved by differentconfigurations of filaments. Variations may include, for example,variations in materials, the number of filaments, the radial positioningof the filaments, the axial positioning of the filaments, the length ofthe filaments, the angle at which the filaments exit the tip, the shapeof the filaments, etc. By varying these parameters, the needle may beconfigured to produce lesions of various sizes and shapes that arepositioned at various locations relative to the tip. Such variations maybe specifically tailored to be used in specific procedures, such as RFneurotomy procedures of particular nerves adjacent to particularvertebrae.

Variations of the materials used for the tip and/or the filaments may beselected to achieve particular lesion sizes, positions, and/or shapes.For example, the tip may comprise (e.g., be made form) a material thatdoes not conduct RF energy, in which case RF energy from the RF probe401 may be conducted by substantially only the deployed filaments. Incertain such embodiments, emitting RF energy from the filaments mayprovide for a lesion with a larger offset from the central longitudinalaxis 223 than would be produced if the tip conducts RF energy and actsas an electrode along with the filaments.

Another material-related variation that may affect lesion shape, size,and/or position is the addition and placement of insulation over the tipand/or over the filaments. For example, by placing a layer of insulationover a proximal part of the portions of the filaments that extend fromthe tip when in the deployed position, the shape of the lesion may bealtered since RF energy may primarily emanate from the distal,non-insulated part of the filaments. For another example, by placing alayer of insulation over a proximal part of the tip, the shape of thelesion may be altered since RF energy may primarily emanate from thedistal, non-insulated part of the tip. Other parts of the filamentsand/or tip may also be covered by an insulating material, for example adistal part of the filaments and/or tip, an intermediate part of thefilaments and/or tip, combinations thereof, and the like, for example asdescribed with respect to FIGS. 3H and 3I.

Moreover, the materials used in making the filaments and tip may beselected based on RF conductivity. For example, by using a material forthe tip that is less conductive of RF energy, the proportion of RFenergy emanating from the tip as compared to that emanating from thefilaments may be altered resulting in a corresponding change in lesionsize, position and/or shape.

The RF needles and RF probes discussed herein may be constructed frommaterials that are Magnetic Resonance Imaging (MRI) compatible (e.g.,titanium, aluminum, copper, platinum, non-magnetic 300 Series StainlessSteel, etc.). In certain such embodiments, MRI equipment may be used toverify the positioning of the needles and/or portions thereof and/ormonitor the progress of an ablation procedure (e.g., RF neurotomy).

Variations of the number of filaments used for needle may be selected toachieve particular lesion sizes, positions and/or shapes. For example,as illustrated in FIG. 7, a third filament 701 may extend from the tip201′ (or other tips described herein such as the tip 211) in a positionbetween filaments 206 a, 206 b. The tips 501 a, 501 b of the filaments206 a, 206 b and a tip 702 of filament 701 may form a polygon 703 thathas a centroid 704. The centroid 704 is offset from the centrallongitudinal axis 223. Such an arrangement may produce a lesion that isoffset from the central longitudinal axis 223 to a different degreethan, and shaped differently than, a lesion created by the needle ofFIG. 5. In general, where a centroid of a polygon formed by the tips offilaments (or, in the case where there are two filaments, the midpointbetween them) is offset from the central longitudinal axis 223, a lesioncreated by such a configuration will be correspondingly offset from thecentral longitudinal axis 223. The filaments 206 a, 206 b, 702 arepositioned at the same filament angle 503 of about 120° as in theembodiment of FIG. 5. Other filament angles 503, in either FIG. 5 orFIG. 7, are also possible. The embodiment illustrated in FIG. 7 has afilament-free angle 504 of about 240°, also the same as in theembodiment of FIG. 5. Other filament-free angles 504, in either FIG. 5or FIG. 7, are also possible. In general, in embodiments in which thefilaments are positioned in a filament angle 503 that is less than about180°, resultant lesions will be offset from the central longitudinalaxis 223 in the direction of the filaments. In embodiments in which thefilaments are positioned in a filament angle 503 that is less than about180°, the filament-free angle is correspondingly greater than about 180°(e.g., greater than about 200° or greater than about 240°).

For another example, as illustrated in FIG. 8, four filaments 801 a-801d are positioned about a tip 201″ (or other tips described herein suchas the tip 211). The tips of the filaments 801 a-801 d may form apolygon 802 that has a centroid 803. The centroid 803 is offset from thecentral longitudinal axis 223. Such an arrangement may produce a lesionthat is offset from the central longitudinal axis 223 in the directionof the centroid 803. The filaments 801 a-801 d are positioned at afilament angle 804 of about 200°. Other filament angles 804 are alsopossible. The embodiment illustrated in FIG. 8 has a filament-free angle805 of about 160°. Other filament-free angles 805 are also possible.FIG. 8 illustrates an embodiment in which the filament-free angle 805 isless than about 180°, but which is capable of producing a lesion offsetfrom the central longitudinal axis 223.

In the herein-described embodiment of FIGS. 2A, 3A, 3B, 5, and 6 withtwo filaments, a midpoint 502 between the filaments was discussed. Inembodiments with more than two filaments, a centroid of a polygon formedby the distal ends of the filaments was discussed. Both the midpointsand the centroids may be considered to be “average” points of thefilaments for their particular configurations. In such embodiments, themidpoint between filaments in two-filament embodiments and the centroidof the polygon in embodiments with more than two filaments may be offsetfrom the central longitudinal axis of the elongate member. For example,the midpoint or centroid may be offset from the central longitudinalaxis by 1 mm or more. In embodiments, the polygon may lie in a planeperpendicular to the central longitudinal axis.

As illustrated in, for example, FIGS. 2A, 2D, 3A, 3C, 3D, 3G-3I, 5, 7,8, 9, and 10, the distal ends of the filaments when fully deployed maybe in a common plane. In some embodiments, the common plane isperpendicular or transverse to the central longitudinal axis. In someembodiments, the common plane is distal to the point 301, 312.

As illustrated in, for example, FIGS. 2A, 2D, 3A, 3C, 3D, 3G-3I, 5, 7,and 10, the filaments of the needle may all be deployed on a common sideof a central plane of the needle (where the central longitudinal axis isentirely within the central plane). In certain such embodiments, thedistal ends of the filaments are all on a common side of the centralplane. Such a configuration may enable the needle to be used to create alesion that is offset from the tip of the needle to the same side of thecentral plane as the deployed filament ends.

As illustrated, for example, in FIGS. 2A, 2D, 3A, 3C, 3D, 3G-3I, and 10,the filaments when fully deployed may point in an at least partiallydistal direction. In this regard, a vector extending longitudinally fromthe distal end of a filament and coinciding with a central axis of theportion of the filament out of the tip 211 has at least some distalcomponent. The fully deployed filaments in the embodiments illustratedin FIGS. 2A, 2D, 3A, 3C, 3D, 3G-3I, and 10 all point in an at leastpartially distal direction.

FIG. 9 illustrates an embodiment in which the filaments are uniformlydistributed about the circumference of the tip 201″″. The needle of FIG.9 includes three filaments 901 a, 901 b, 901 c distributed substantiallyequally about the circumference of the tip 201″″, the angles 902 a, 902b, 902 c between the filaments 901 a, 901 b, 901 c each being about120°. Such a needle may be operable to produce a lesion that isgenerally centered along the central longitudinal axis 223. However, theposition of the produced lesion longitudinally along the centrallongitudinal axis 223 may be determined by the configuration (e.g.,length, deployment angle, etc.) of the filaments. For example,relatively longer filaments may be operable to produce lesions that arepositioned distal to lesions produced by configurations with relativelyshorter filaments. For another example, in an embodiment in which thefilament 901 b is longer than the filaments 901 a, 901 c, the needle maybe operable to create a lesion that is offset from the tip of the needletowards the filament 901 b. For yet another example, in an embodiment inwhich the filaments 901 a, 901 b are longer than the filament 901 c, theneedle may be operable to create a lesion that is offset from the tip ofthe needle towards the filaments 901 a, 901 b.

Referring again to FIG. 7, if the filament 701 was distal to thefilaments 206 a, 206 b, the resultant lesion may be longer along thecentral longitudinal axis 223 than lesions resulting from an embodimentin which the filaments 206 a, 206 b, 701 are each positioned alongsubstantially the same plane perpendicular or transverse to the centrallongitudinal axis 223. In another variation, as deployed, two or morefilaments may be at the same radial position and at different axialpositions. Such embodiments may include multiple rows of filaments.

Referring again to FIGS. 5 and 6, if the lengths of the deployedportions of the filaments 206 a, 206 b were increased, the needle may becapable of producing lesions that are more distally positioned thanlesions created by the embodiment as shown in FIGS. 5 and 6. The effectsof lengthening or shortening the deployed length of the filaments may besimilar to those discussed herein with respect to partially deployingfilaments.

In some embodiments, the needle includes filaments having deployedportions with different lengths. In certain embodiments in which all ofthe filaments are deployed and/or retracted by a common actuator and/orare part of the same wire, variations in filament lengths may beachieved by varying the overall length of the filaments. For example,the distal end of a shorter filament may be retracted further into thetip or elongate member than the distal end of a longer filament. Theeffects of lengthening or shortening the length of the deployed portionsof the filaments may be similar to those discussed herein with respectto variations in the axial positioning of filaments emergence from thetip of the needle and/or with respect to partially deploying filaments.

The angle at which a filament exits a tip (e.g., the angle 601 of FIG.6) may be varied to achieve particular lesion sizes, positions, and/orshapes. For example, if the angle 601 in FIG. 6 was about 60°, theneedle may be operable to produce a lesion that has a larger maximumcross-sectional dimension in a plane perpendicular to the centrallongitudinal axis 223 than if the angle 601 was about 30°, for examplebecause the filaments can emanate RF energy at a distance further awayfrom the central longitudinal axis. In some embodiments, the filamentscan be deployed at different angles 601 relative to the centrallongitudinal axis 223.

Referring again to FIG. 10, the deployed portions of the filaments 1001a, 1001 b may be curved. As described herein, the term “curved” may meana continuous curve, a curve in combination with a straight section, aplurality of curves in different directions, combinations thereof, andthe like. Such curvatures may be achieved, for example, by filaments1001 a, 1001 b comprising shape memory material (e.g., Nitinol) orspring material. When the filaments 1001 a, 1001 b are retracted, theshape of the tip 201 and/or the elongate member 203 may cause thefilaments 1001 a, 1001 b to be in constrained straightenedconfigurations. As the filaments 1001 a, 1001 b are advanced toward thefully deployed position, they become unconstrained and return to theircurved shapes as shown in FIG. 10. The deployed shape of the filaments1001 a, 1001 b may be predetermined, or the filaments 1001 a, 1001 b maycomprise (e.g., be made from) a material that may be shaped by a userprior to insertion. The filaments of other embodiments described herein(e.g., FIGS. 3A, 3C, 3D, and 3G-3I) may also be curved. In someembodiments, one filament is curved and one filament is straight.

The curved filaments 1001 a, 1001 b of FIG. 10 are positioned in planesthat include the central longitudinal axis 223. In other embodiments,the filaments 1001 a, 1001 b may be curved in other directions, such asin a corkscrew arrangement. This may be beneficial to assist thefilaments in remaining anchored to the tissue during delivery of RFenergy. The curved filaments 1001 a, 1001 b of FIG. 10 may be operableto produce a lesion that is flatter in a plane perpendicular to thecentral longitudinal axis 223 than, for example, the straight filaments206 a, 206 b of FIG. 6.

In the embodiment illustrated in FIGS. 2A and 2B, the filaments 206 a,206 b are illustrated as running the entire length of the elongatemember 203 from the filament hub 221 to the tip 201. In someembodiments, a single member may run along at least part of the elongatemember 203 and the filaments 206 a, 206 b may be interconnected to thesingle member at a point proximal to the tip 201.

The illustrated embodiments show all of the filaments of a givenembodiment as commonly deployed or retracted. In some embodiments, oneor more filaments may be individually deployed and/or retracted. In someembodiments, a plurality of filaments may exit from the tip at a commonlocation and form a fan-like arrangement as they are deployed.

Deployment of filaments discussed herein has been described as movementof the filaments relative to a stationary tip. In some embodiments, thefilaments may be deployed by pulling the tip back relative to thefilaments (e.g., movement of the tip relative to stationary filaments).Movement of the tip rather than the filaments may be advantageous, forexample, in embodiments in which the needle is initially advanced untilin contact with bone to ensure proper positioning relative to targettissue, and then the tip may be retracted, leaving the filaments (e.g.,curved shape memory filaments) in a precise, known position. In someembodiments, the filaments may be deployed by advancing the filamentsand retracting the tip.

Referring again to FIGS. 2A and 2B, the hub 204 may be fixedly attachedto the elongate member 203. The hub 204 may be the primary portion ofthe needle 103 gripped by the user during insertion and manipulation ofthe needle 103. The hub 204 may include an asymmetric feature, such asan indicator 225, that is in a known orientation relative to theasymmetry of the tip 201. In this regard, the indicator 225 may be usedto communicate to the user the orientation of the tip 201 within apatient. For example, in the embodiment illustrated in FIG. 2A, theindicator 225 is fixed at an orientation circumferentially opposite tothe filament slots 304 a, 304 b. Internally, the hub 204 may include acavity 213 sized to house a longitudinal protrusion 218 of the actuator216. The hub 204 may include a hole through which a projection 215 mayproject into the interior of the cavity 213 to control the motion of theactuator 216 relative to the hub 204 and to secure the actuator 216 tothe hub 204. The hub 204 may comprise (e.g., be made from) anyappropriate material (e.g., a thermoset plastic, Makrolon® 2548,available from Bayer).

The actuator 216 may be used to control the motion to deploy and/orretract the filaments 206 a, 206 b. The actuator 216 is operable to moverelative to the hub 204, the elongate member 203, and the tip 201 (e.g.,parallel to the central longitudinal axis 223). The actuator 216includes the longitudinal protrusion 218 extending into the cavity 213of the hub 204. The outer surface of the longitudinal protrusion 218includes a helical track 219 sized to accommodate the projection 215. Inthis regard, as the actuator is rotated relative to the hub 204 (e.g.,by a user to deploy the filaments 206 a, 206 b), the helical track 219and the projection 215 combine to cause the actuator 216 to movelongitudinally (e.g., parallel to the central longitudinal axis 223).The actuator 216 comprises an interface portion 217 that may be grippedby a user when rotating the actuator 216. The interface portion 217 maybe knurled or otherwise textured to enhance the user's ability to rotatethe actuator 216. The hub 204 may also include a textured or shapedfeature (e.g., the indicator 225) configured to enhance the user'sability to rotate the actuator 216 relative to the hub 204. Thelongitudinal protrusion 218 of the actuator 216 may include an innercavity 226 sized to accept a filament hub 221 and to allow the filamenthub 221 to rotate freely relative to the actuator 216. In this regard,the linear motion of the actuator 216 may be transmitted to the filamenthub 221 while the rotational motion of the actuator 216 may not betransmitted to the filament hub 221.

The actuator 216 may include a Luer fitting 220 or any other appropriatefitting type on a proximal end thereof. The Luer fitting 220 may be influid communication with the lumen 222 and provide a connection suchthat fluid may be delivered into the lumen 222 and to the fluid port 210of the tip 201, 211. The Luer fitting 220 may also be configured toallow for the insertion of the RF probe 401 into the lumen 222. Theactuator 216 may comprise any appropriate material (e.g., Pro-fax 6523polypropylene homopolymer, available from LyondellBasell Industries).

The filaments 206 a, 206 b may be fixedly interconnected to the filamenthub 221. In this regard, the longitudinal movement of the filament hub221 due to the actuator 216 may be communicated to the filaments 206 a,206 b to deploy and retract the filaments 206 a, 206 b upon rotation ofthe actuator 216. The filament hub 221 may comprise any appropriatematerial (e.g., Pro-fax 6523 polypropylene homopolymer, available fromLyondellBasell Industries).

The user can deploy or retract the filaments 206 a, 206 b by twisting orrotating the actuator 216. For example, as illustrated, acounterclockwise (as seen from the viewpoint of FIG. 5) rotation of theactuator 216 relative to the hub 204 will result in the deployment(extension) of the filaments 206 a, 206 b, while a clockwise rotation ofthe actuator 216 relative to the hub 204 will result in the retractionof the filaments 206 a, 206 b.

The filaments 206 a, 206 b may be partially deployed or retracted bypartially rotating the actuator 216 relative to the hub 204. Theactuator 216 and/or the hub 204 may include markings to indicate theposition of the filaments 206 a, 206 b (e.g., the depth or extent ofdeployment). The actuator 216 and/or the hub 204 may include detents toprovide audible and/or tactile feedback of the position of the filaments206 a, 206 b.

In some embodiments, the filaments may be deployed at the user'sdiscretion to a deployed position proximal to, at, or distal to a planeperpendicular or transverse to the central longitudinal axis 223 at thepoint 301, 312. For example, in some embodiments, full (e.g., 3/3)rotation of the actuator 216 may deploy the filaments in a fullydeployed position that is distal to a plane perpendicular or transverseto the central longitudinal axis 223 at the point 301, 312, partial(e.g., 2/3) rotation of the actuator 216 may deploy the filaments in apartially deployed position that is at a plane perpendicular ortransverse to the central longitudinal axis 223 at the point 301, 312,and partial (e.g., 1/3) rotation of the actuator 216 may deploy thefilaments in a partially deployed position that is proximal to a planeperpendicular or transverse to the central longitudinal axis 223 at thepoint 301, 312. The actuator 216 and/or the hub 204 may include featuressuch as stops or detents to provide audible and/or tactile feedbackregarding the extent of deployment (e.g., at 0/3, 1/3, 2/3, and 3/3)and/or the position of the filaments 206 a, 206 b (e.g., fullyretracted, 1/3 deployed, 2/3 deployed, and fully deployed). Otherfractions are also possible, including fractions at uneven intervals(e.g., a combination of ⅓, ½, and ⅘). In certain embodiments, selectablecontrolled partial deployment allows for controlled adaptation of thelesion to any particular shape and/or conformance of the filaments to aspecific anatomy (e.g., boney anatomy).

FIGS. 17A-17E illustrate components of the mechanism at the proximal end205 of the needle 103 of FIG. 2D. The mechanism may also be used, forexample, with the needle 103 of FIG. 2A and other needles describedherein. The components described with respect to FIGS. 17A-17E mayinclude features described herein with respect to FIGS. 2B and 2C, andthe components described herein, for example with respect to FIGS. 2Band 2C may include features described herein with respect to FIGS.17A-17E. Combinations of components are also possible.

FIG. 17A is an exploded view of components of the deployment mechanismof FIG. 2D. The mechanism comprises an advancing hub or slide member1710, a spin collar or actuator 1720, and a main hub 1730. FIG. 17B is across-sectional view of the advancing hub 1710, the spin collar 1720,and the main hub 1730 assembled together, as well as half of the wire206 illustrated in FIG. 2E. The advancing hub 1710 includes a stem orlongitudinal protrusion 1712. The spin collar 1720 includes a lumen 1721extending from the proximal end to the distal end. The main hub 1730includes a lumen 1731 extending from the proximal end to the distal end.When assembled, the stem 1712 of the advancing hub 1710 is in the lumen1721 of the spin collar 1720 and in the lumen 1731 of the main hub 1730.The advancing hub 1710 may include an annular protrusion 1714 that mayinteract with an annular protrusion of the spin collar 1720 (e.g., theannular protrusion 1714 having a larger diameter than the annularprotrusion 1724) to inhibit the stem 1712 from exiting the proximal endof the lumen 1721. In some embodiments, the annular protrusions 1714,1724 include tapered surfaces that may interact to allow insertion ofthe stem 1712 and the annular protrusion 1714 into the lumen 1721 andperpendicular surfaces to inhibit the annular protrusion 1714 and thestem 1712 from exiting the proximal end of the lumen 1721. The main hub1730 includes a stem or longitudinal protrusion 1734. When assembled,the stem 1734 of the main hub 1730 is in the lumen 1721 of the spincollar 1720. Other interactions between the advancing hub 1710, the spincollar 1720, and the main hub 1730 are described herein, for examplewith respect to FIGS. 17C-17E.

FIG. 17C is a perspective view of an example embodiment of the advancinghub 1710 and the wire 206 of FIG. 2E. The stem 1712 of the advancing hub1710 comprises a U-shaped recess 1713 configured to interact with thebent proximal portion of the wire 206. Other shapes of the recess 1713are also possible (e.g., V-shaped). The recess 1713 may complement theshape of the proximal end of the wire 206. In some embodiments, thewidth of the recess 1713 is slightly smaller (e.g., about 0.001 inches(approx. about 0.025 mm) smaller) than the diameter of the wire 206 suchthat after being press-fit, the wire 206 is fixedly interconnected tothe advancing hub 1710.

In some embodiments, the stem 1712 is shaped as illustrated in FIG. 17C,including a perpendicular or transverse cross-section that includes flatsurfaces (e.g., the surface comprising the top of the recess 1713) andarcuate surfaces, for example an ellipse with squared ends. The lumen1731 of the main hub 1730 may comprise complementary surfaces, forexample in a wider proximal portion, such that when the stem 1712 is inthe lumen 1731, the advancing hub 1710 is in a fixed rotational positionrelative to the main hub 1710. Other shapes and rotational fixationconfigurations are also possible.

The proximal end of the advancing hub 1710 comprises a fitting 220(e.g., a Luer fitting or any other appropriate fitting). When assembled,the fitting 220 is proximal to the spin collar 1720. The advancing hub1710 comprises a lumen 1711 extending from the proximal end to thedistal end. A fluid delivery device such as a syringe may be attached tothe fitting 220 to deliver fluid through the lumen 1711 and then throughthe lumen 1731 of the main hub, the lumen 308 of the elongate member203, the lumen 306 c of the tip 211, and out the fluid port 210 of thetip 211. The RF probe 401 may be inserted into the lumen 1711, then intothe lumen 1731 of the main hub, then into the lumen 308 of the elongatemember 203, then into the lumen 306 c of the tip 211. The RF probe 401may include a fitting configured to interact with the fitting 220. Thelumen 1711 may include a wide diameter portion in the area of thefitting 220 and a narrow diameter portion in the area of the stem 1712,and a tapered surface 1715 transitioning from the wide diameter portionto the narrow diameter portion. The tapered surface 1715 may help directfluid and/or an RF probe 401 into the narrow diameter portion. In someembodiments, the narrow diameter portion of the lumen 1711 has adiameter between about 0.005 inches and about 0.05 inches (approx.between about 0.13 mm and about 1.3 mm), between about 0.01 inches andabout 0.03 inches (approx. between about 0.25 mm and about 0.76 mm),between about 0.015 inches and about 0.025 inches (approx. between about0.38 mm and about 0.64 mm) (e.g., about 0.02 inches (approx. about 0.5mm)), combinations thereof, and the like. In some embodiments, thenarrow diameter portion of the lumen 1711 has a diameter that is nolarger than the diameter of any other lumen of the needle 103 such thatfluid pressure will default to the distal end of the needle 103. Forexample, the narrow diameter portion of the lumen 1711 may have adiameter of about 0.02 inches (approx. about 0.5 mm), the narrowdiameter portion of the lumen 1731 may have a diameter of about 0.05inches (approx. about 1.3 mm), the lumen 308 of the elongate member 203may have a diameter of about 0.05 inches (approx. about 1.3 mm), and thelumen 306 c may have a width of about 0.02 inches (approx. about 0.5mm). In some embodiments, the lumen 306 c may be slightly smaller thanthe narrow diameter portion of the lumen 1711 and have the same effect,for example due to small losses of fluid through the lumens 306 a, 306 band out the filament ports 304 a, 304 b, which may be acceptable becauseanesthesia and dye, for example, may permeate through fluid andproximate to the filament ports 304 a, 304 b even if substantially onlydispensed from the fluid port 210. In some embodiments, the advancinghub 1710 comprises a polymer (e.g., Pro-fax 6523 polypropylenehomopolymer, available from LyondellBasell Industries).

FIG. 17D is a cross-sectional view of an example embodiment of a spincollar 1720. The cross-section is along the same line as in FIG. 17B,but further features are visible because not blocked by the advancinghub 1710 or the main hub 1730. As illustrated in FIG. 17B, the lumen1721 is configured to at least partially contain the stem 1712 and thestem 1734, and not to contact fluid or an RF probe 401. The lumen 1721comprises a helical track 1722 sized to interact with a correspondinghelical thread 1735 (FIG. 17A) on the stem 1734 of the main hub 1730. Asthe spin collar 1720 is rotated relative to the main hub 1730 (e.g., bya user stabilizing the needle and gripping the main hub 1730 with thenon-dominant hand and manipulating the spin collar 1720 with thedominant hand), for example, to deploy the filaments 206 a, 206 b, thehelical track 1722 and the helical thread 1735 interact to cause thespin collar 1720 and the advancing hub 1710 to move longitudinallyparallel to the central longitudinal axis 223. In this regard, a linearmotion of the advancing hub 1710 relative to the main hub 1730 may becreated while the rotational motion of the spin collar 1720 may not betransmitted to the advancing hub 1710 and the main hub 1730. In someembodiments, between about 1.25 turns and about 1.5 turns of the spincollar 1720 fully deploys the filaments 206 a, 206 b. In someembodiments, between about 0.75 turns and about 1.25 turns (e.g., one360° rotation) of the spin collar 1720 fully deploys the filaments 206a, 206 b. The configuration of the helical track 1722 and the helicalthread 1735 may be adjusted to provide varying levels of filamentdeployment with varying levels of rotation of the spin collar 1720. Anouter surface of the spin collar 1720 may be textured or includefeatures 1723 to assist the user in gripping and twisting or rotatingthe spin collar 1720 relative to the main hub 1730. In some embodiments,the spin collar comprises the helical thread 1735 and the main hub 1730comprises the helical track 1722. In some embodiments, the spin collar1720 comprises a polymer (e.g., Pro-fax 6523 polypropylene homopolymer,available from LyondellBasell Industries).

FIG. 17E is a cross-sectional view of an example embodiment of the mainhub 1730, taken along the line 17E-17E of FIG. 17B, in exploded viewwith an example embodiment of an elongate member 203. The proximal endof the elongate member 203, to the right in FIG. 17E, includes a partialcircumferential portion 1736. The distal end lumen 1731 of the main hub1730 includes a complementary partial circumferential portion 1737. Thepartial circumferential portions 1736, 1737 can cause the elongatemember 203 to be in a fixed and known rotational orientation with themain hub 1730, for example after assembly because the relative positionof the indicator 1733 and the partial circumferential portion 1737 isknown. For example, the distal end of the elongate member 203, to theleft in FIG. 17E, includes the filament ports 304 a, 304 b on the sameside as the partial circumferential portion 1736. Other partialcircumferential portions and other complementary shapes are alsopossible. For example, the partial circumferential portions may compriseinterlocking teeth. In some embodiments, the thickness of the partialcircumferential portion 1737 is substantially the same as the thicknessof the walls of the elongate member 1736 to provide a smooth transitionbetween the lumen 1731 and the lumen 308. In some embodiments, the mainhub 1730 comprises clear polycarbonate (e.g., thermoset plastic such asMakrolon® 2548, available from Bayer). In some embodiments, the elongatemember comprises a hypotube (e.g., comprising 300 Series StainlessSteel) with features such as the filament ports 304 a, 304 b and thepartial circumferential portion 1736 cut out (e.g., by laser,mechanical, chemical, or other cutting methods).

Other types of mechanisms may be used to control deployment andretraction of the filaments. For example, in some embodiments, themechanism includes a spring configured to bias the filaments 206 a, 206b toward a predetermined position (e.g., fully deployed, fullyretracted), analogous to a spring loaded mechanism used in retractableballpoint pens. For another example, the mechanism may include a rollerwheel, for example incorporated into the hub 204, that would advance orretract the filaments 206 a, 206 b upon rotation, for example with auser's thumb. For yet another example, the hub 204 and the actuator 216may interact via complimentary threaded features. As the actuator 216 isthreaded into the hub 204, the filaments 206 a, 206 b would advance, andas the actuator 216 is threaded out of the hub 204, the filaments 206 a,206 b would retract. For still another example, a Touhy-Borst typemechanism could be incorporated to control the deployment and retractionof the filaments 206 a, 206 b. Any other appropriate mechanism forcontrolling linear motion of the filaments 206 a, 206 b may beincorporated into the needle 103. Any of the mechanisms described hereinmay be used for controlling deployment and retraction of the filamentsof any of the embodiments described herein. For example, the mechanismsillustrated in FIGS. 2A-2D and 17A-17E may be used to deploy and retractthe filaments in FIGS. 3A, 3C, 3D, 3G-3I, and 5-10.

FIG. 2C is a partial cut away and partial cross-sectional view of aportion of an alternate embodiment of a mechanism 230 comprising a hub231 and actuator 232 that may be part of a needle 103 used in an RFneurotomy procedure. The hub 231 may be fixedly attached to the elongatemember 203. The hub 231 may be the primary portion of the needle 103gripped by the user during insertion and manipulation of the needle 103.The hub 231 may include an asymmetric feature, such as an indicator 233,that is in an known orientation relative to the asymmetry of the tip201. In this regard, the indicator 233 may be used to communicate to theuser the orientation of the tip 201 within a patient. Internally, thehub 231 may include a cavity 234 sized to house a longitudinalprotrusion 235 of a slide member 236. The longitudinal protrusion 235may include a keyway or key slot 237 that may run along a longitudinaldirection of the longitudinal protrusion 235. The internal surface ofthe hub 231 through which the longitudinal protrusion 235 moves mayinclude a mating key (not shown) configured to fit and slide in the keyslot 237. Together, the key slot 237 and mating key of the hub 231 maylimit the slide member 236 to a linear motion parallel to the centrallongitudinal axis 223.

The filaments 206 a, 206 b may be fixedly connected to the longitudinalprotrusion 235 of the slide member 236 for longitudinal movementtherewith. In this regard, distal movement (e.g., movement to the rightas shown in FIG. 2C) of the longitudinal protrusion 235 relative to thehub 231 may cause extension of the filaments 206 a, 206 b relative tothe hub 231, the elongate member 203, and the tip 201. For example,distal movement of the longitudinal protrusion 235 may move thefilaments 206 a, 206 b from a retracted position to a deployed position.For another example, proximal movement (e.g., movement to the left asshown in FIG. 2C) of the longitudinal protrusion 235 relative to the hub231 may result in retraction of the filaments 206 a, 206 b relative tothe hub 231, the elongate member 203, and the tip 201.

The hub 231 may be made from any appropriate material (e.g., a thermosetplastic, Makrolon® 2548, available from Bayer). The hub 231 may be atleast partially transparent such that the position of the longitudinalprotrusion 235 and/or other components of the hub 231 may be observableby a user. The hub 231 may further include demarcations (e.g., molded orprinted marks) such that the amount of extension of the filaments 206 a,206 b may be determined from the position of the longitudinal protrusion235 and/or other components relative to the demarcations.

An actuator 232 may be used to control the motion to deploy and/orretract the filaments 206 a, 206 b fixedly connected to the longitudinalprotrusion 235. The actuator 232 may be generally tubular such that itfits around a longitudinal hub projection 238 projecting from theproximal end of the hub 231. At least a portion of the cavity 234 may bein the longitudinal hub projection 238. The actuator 232 may alsoinclude an annular feature 239 configured to fit in an annular slot 240in the slide member 236. The annular feature 239 may be sized relativeto the annular slot 240 such that the actuator 232 may rotate relativeto the slide member 236 about the central longitudinal axis 223 or anaxis parallel thereto while the position of the actuator 232 relative tothe slide member 236 along the central longitudinal axis 223 remainsfixed. In this regard, the actuator 232 and the slide member 236 may beconfigured to move in tandem relation along the central longitudinalaxis 223. The annular feature 239 and annular slot 240 may be configuredsuch that, during assembly, the actuator 232 may be pressed onto theslide member 236 and the annular feature 239 may snap into the annularslot 240.

The inner surface of the actuator 232 may include a helical track 241sized to accommodate a corresponding mating helical thread 242 on thelongitudinal hub projection 238. In this regard, as the actuator 232 isrotated relative to the slide member 236 and the hub 231 (e.g., by auser to deploy the filaments 206 a, 206 b), the helical track 241 andthe helical thread 242 interact to cause the actuator 232 and the slidemember 236 to move longitudinally along the central longitudinal axis223. In this regard, a linear motion of the slide member 236 relative tothe hub 231 may be created while the rotational motion of the actuator232 may not be transmitted to the slide member 236 and the hub 231. Anouter surface of the actuator 232 may be textured or include features toassist the user in gripping and twisting or rotating the actuator 232relative to the hub 231. In some embodiments, the longitudinal hubprojection 238 comprises the helical track 241 and the inner surface ofthe actuator 232 comprises the helical thread 242.

The proximal end of the slide member 236 may include a Luer fitting 243or any other appropriate fitting type. The Luer fitting 243 may be influid communication with a lumen passing through the slide member 236and may provide a connection such that fluid may be delivered throughthe Luer fitting 243 and into the lumen of the slide member 236. Inturn, the lumen of the slide member 236 may be in fluid communicationwith the cavity 234 of the hub 231, which may in turn be in fluidcommunication with a lumen in the elongate member 223 (e.g., the lumen222). The lumen in the elongate member 223 may be in fluid communicationwith the tip 201 (e.g., the fluid port 210). In this regard, fluid mayflow into the Luer fitting 243, into and through the lumen in the slidemember 236, into and through the cavity 234 of the hub 231, into andthrough the elongate member 223, and out from fluid portion 210 of thetip 201. The Luer fitting 243, the lumen in the slide member 236, thecavity 234 of the hub 231, and the lumen of the elongate member 223 mayall also be configured to allow for the insertion of the RF probe 401therethrough. The protrusion 235 and the cavity 234 of the longitudinalhub projection 238 may be sized and/or configured to form a fluid sealtherebetween, allowing fluid delivered under pressure through the Luerfitting 220 to flow through the cavity 238 and into the elongate member203 substantially without leaking past the interface between theprotrusion 235 and the cavity 234 of the longitudinal hub projection238.

As described herein, the filaments 206 a, 206 b may be fixedlyinterconnected to the slide member 236. Axial movement of the slidemember 236 due to the actuator 232 may be thereby communicated to thefilaments 206 a, 206 b to deploy and retract the filaments 206 a, 206 bupon rotation of the actuator 232. The slide member 236 may be made fromany appropriate material (e.g., Pro-fax 6523 polypropylene homopolymer,available from LyondellBasell Industries). The actuator 232 may be madefrom any appropriate material (e.g., Pro-fax 6523 polypropylenehomopolymer, available from LyondellBasell Industries).

The user can deploy or retract the filaments 206 a, 206 b by twisting orrotating the actuator 232. By partially rotating the actuator 232relative to the hub 231, the filaments 206 a, 206 b may be partiallydeployed or retracted. The actuator 232 and/or hub 231 may includedetents to provide audible and/or tactile feedback of the position ofthe filaments 206 a, 206 b. The detents may be configured such thataudible and/or tactile feedback associated with engagement of a detentcoincides with a predetermined amount of deployment or retraction of thefilaments 206 a, 206 b, as described herein. In this regard, suchaudible and/or tactile feedback may be used in determining filamentposition.

In some embodiments, the needle 103 is a multipolar (e.g., bipolar)device in contrast to the monopolar devices described herein. In certainsuch embodiments, the filaments are isolated from each other and/or fromthe tip to enable bipolar operation (e.g., the filaments having onepolarity and the tip having a second polarity, one filament having onepolarity and one filament and the tip having a second polarity, onefilament having one polarity and one filament having a second polarity,etc.). In embodiments in which the needle 103 comprises more than twofilaments, elements may be included to allow for selection of thepolarity of the certain filaments to aid in lesion shape, size, and/orposition control. In some embodiments, the needle 103 may be used ineither a monopolar mode or in a bipolar mode as selected by the user.For example, RF probes 401 may include shapes, insulating features, etc.configured to produce monopolarity or bipolarity.

The herein-described embodiments of needles may be used in spinal RFneurotomy procedures, which will now be described. In general, for an RFneurotomy procedure, the patient may lie face down on a table so thatthe spine of the patient is accessible to the user. At any appropriatetime before, during, and/or after the procedure, the user may useimaging equipment, such a fluoroscope, to visualize the patient'sanatomy and/or to visualize the positioning of equipment (e.g., theneedle relative to a target volume).

The patient may be administered sedatives and/or intravenous fluids asappropriate. The skin of the patient surrounding the procedure locationmay be prepared and maintained using an appropriate sterile technique.In embodiments in which the needle is monopolar, a return electrode pad104 may be attached to the patient. A local anesthetic may be injectedsubcutaneously where the needle will be inserted or along theapproximate path of the needle, for example through the needle itself orthrough a different needle.

With the filaments in the retracted position, the needle may beintroduced into the patient and moved to a target position relative to atarget portion of a target nerve or to a target position relative to atarget volume in which the target nerve is likely situated (all of whichare generally referred to herein as the target nerve or portion of thetarget nerve). The target nerve may be an afferent nociceptive nervesuch as, for example, a medial branch nerve proximate a lumbar facetjoint. Introduction of the needle into the patient may includepercutaneously using the tip of the needle to pierce the skin of thepatient. The moving of the needle may include navigating toward thetarget position using fluoroscopic guidance. Furthermore, the moving ofthe needle may include advancing the needle to an intermediate positionand then repositioning the needle to the target position. For example,the needle may be advanced until it contacts a bone or other structureto achieve the intermediate position. This may be followed by retractingthe needle a predetermined distance to achieve the target position. Sucha procedure may be facilitated by the markers 224 or collar discussedherein.

During the moving of the needle or after the target position has beenachieved, the needle may be used to inject an anesthetic and/or a dyeproximate to the target nerve. The dye may increase contrast influoroscopic images to assist in visualizing the patient's anatomy,which may aid the user in guiding and/or verifying the position of theneedle.

The needle may be rotated about the central longitudinal axis of theelongate member of the needle to achieve a desired orientation relativeto the target nerve. For example, the needle may be rotated such that alesion created with the needle with the filaments deployed will beoffset from the central longitudinal axis toward the target nerve. Suchrotation of the needle may be performed prior to insertion of the needleinto the patient and/or after insertion into the patient. For example,the user may rotate the needle prior to insertion such that the needleis generally in the desired rotational orientation. Then, afterachieving the target position, the user may fine tune the rotationalorientation of the needle by rotating the needle to a more preciseorientation. As described herein, the hub or another portion of theneedle outside the patient's body may indicate the rotationalorientation of the needle.

Once the target position and desired rotational orientation have beenachieved, the next step may be to advance one or more filaments of theneedle relative to the tip of the needle. The particular needle used fora procedure may have been selected to enable the creation of aparticular sized and shaped lesion at a particular position relative tothe needle. The particular needle used may be of any appropriateconfiguration discussed herein (e.g., any appropriate number offilaments, any appropriate filament positioning, monopolar or bipolar,any appropriate deployment and retraction mechanism, etc.).

In embodiments in which the needle is configured as illustrated in FIGS.5 and 6 (e.g., about 120° apart), the advancement of filaments mayinclude advancing the filaments such that when the filaments are intheir respective deployed positions, a midpoint between a distal end ofthe first filament and a distal end of the second filament is offsetfrom the central longitudinal axis of the needle, and the filamentendpoints are distal to the tip of the needle. Such deployment mayenable the needle to be used to create a lesion that is offset from thetip of the needle toward the midpoint between the deployed filamentends. The lesion created may also be positioned at least partiallydistal to the tip of the needle.

FIG. 11A is an illustration of an example set of isotherms 1010 a-1010 cthat may be created with the needle 103 of FIG. 2A. As illustrated bythe set of isotherms 1010 a-1010 c, RF energy emanating from the tip 201and from the filaments 206 a, 206 b, may produce a region of elevatedtemperature about the tip 201 and the filaments 206 a, 206 b. Theisotherms 1010 a-1010 c may be offset from the central longitudinal axis223 such that a centroid of the isotherms as viewed in FIG. 11A isoffset from the central longitudinal axis 223 in the direction of thefilaments 206 a, 206 b. The centroid of the isotherms 1010 a-1010 c asviewed in FIG. 11A may also be distal relative to the tip 201 andbetween the tip 201 and the distal ends of the deployed filaments 206 a,206 b. The isotherms 1010 a-1010 c may also be shaped such that, asviewed in FIG. 11A, the isotherms 1010 a-1010 c have a maximumcross-sectional dimension along the central longitudinal axis 223 thatis greater than a maximum cross dimension in the plane of FIG. 11Aperpendicular to the central longitudinal axis 223. As visible in theillustrated orientation of FIG. 11B, the isotherms 1010 a-1010 c mayhave a maximum cross-sectional dimension along the central longitudinalaxis 223 that is greater than a maximum cross-sectional dimensionperpendicular to the plane of FIG. 11A and perpendicular to the centrallongitudinal axis 223.

The offset of the centroid of the isotherms 1010 a-1010 c from thecentral longitudinal axis 223 may result in greater lesion width in aplane perpendicular to the central longitudinal axis 223, as compared toa similarly-sized straight needle with no filaments. The offset of thecentroid of the isotherms 1010 a-1010 c may also allow for projection ofthe centroid of a corresponding lesion volume in a direction away fromthe central longitudinal axis 223. By way of example, such offsets mayadvantageously enable the execution of the example procedures describedherein. Such offsets may advantageously enable the creation of lesionvolumes distal (relative to the needle 103) to potentially interferingstructures (e.g., an ossified process). Such offsets may advantageouslyenable the needle 103 to be inserted into a patient at a more desirableangle (e.g., closer to perpendicular to the surface of the patient suchas within 30° of perpendicular to the surface of the patient), at a moredesirable piercing location, and/or through more desirable tissue thanmay be attempted using a needle without offset lesion capabilities.

FIG. 11B is an illustration of an example lesion 1011 that may becreated with the needle 103 of FIG. 2A. In FIG. 11B, the needle 103 hasbeen placed perpendicular to a surface 1012. The surface 1012 may, forexample, be the surface of a bone, such as a lumbar vertebra. Asillustrated, the filaments 206 a, 206 b are deployed such they areproximate to the surface 1012. In some embodiments, contact with thesurface 1012 might undesirably deform the filaments 206 a, 206 b, butsuch contact may be avoided, for example by the needle advancement andretraction procedures described herein. The lesion 1011 has a widthalong the surface 1012 that is wider than would be created by the needle103 if the filaments 206 a, 206 b were not deployed. Such capabilitiesmay, for example, be advantageous where a target structure (e.g., anerve) is known to be positioned along the surface 1012, but its exactposition is unknown. In such a case, the needle 103 may be positionedgenerally perpendicular to the surface 1012 to achieve the illustratedlesion width along the surface 1012, whereas achieve the same lesionwidth along the surface 1012 using a the needle 103 without thefilaments 206 a, 206 b deployed would require either multiplerepositioning steps or placement of the needle 103 generally parallel tothe surface 1012.

FIG. 11C is an illustration of an example lesion 1022 that may becreated with a single-filament needle 1020. The single-filament needle1020 may be similar to the needle 103, although the single-filamentneedle 1020 includes only a single filament 1021. The filament 1021 maybe configured similarly to the filaments 206 a, 206 b. Thesingle-filament needle 1020 with the filament 1021 deployed may beoperable to produce a lesion 1022 that is a flattened version (e.g.,thinner in a direction perpendicular to the central longitudinal axis223, which is the left to right direction as illustrated in FIG. 11C) ofa lesion that may be produced by the needle 103 with two filaments 206a, 206 b deployed. The capability to produce such a lesion shape may bebeneficial when it is desirable to have a relatively large lesion in aparticular direction (e.g., to compensate for the variability oflocation of a target nerve) and a relatively small lesion width inanother direction (e.g., to avoid a structure such as viscera or apatient's skin). As described herein, certain embodiments of the needle103 may allow differential or selective deployment and/or activation ofthe filaments 206 a, 206 b such that the needle 103 may imitate thesingle-filament needle 1020.

In embodiments in which the needle is configured such that all of thefilaments of the needle are deployed on a common side of a central planeof the needle (in which the central longitudinal axis is entirely withinthe central plane), the advancement of filaments may include advancingthe filaments such that when the filaments are in their respectivedeployed positions, the distal ends of all of the filaments are on acommon side of the central plane. Such deployment may enable the needleto be used to create a lesion that is offset from the tip of the needleto the same side of the central plane as the deployed filament ends. Thelesion created may also be positioned at least partially distal to thetip of the needle.

In embodiments in which the needle is configured as illustrated in FIG.7 or 8, the advancement of filaments may include advancing the filamentssuch that when the filaments are in their respective deployed positions,each filament distal end defines a vertex of a polygon whose centroid isoffset from a central longitudinal axis of the needle. Such deploymentmay enable the needle to be used to create a lesion that is offset fromthe tip of the needle toward the centroid. The lesion created may alsobe positioned at least partially distal to the tip of the needle.

The advancement of the filaments may be achieved using any of themechanisms discussed herein. For example, in the embodiment of FIG. 2A,rotating the actuator 216 relative to the hub 204 may cause thefilaments to advance to the deployed position. The advancement of thefilaments may be performed such that each of the plurality of filamentspasses through a surface of the needle that is parallel to the centrallongitudinal axis of the needle. In some embodiments, the filaments ofthe needle may be advanced to a position that is an intermediateposition between the retracted position and the fully deployed position.The degree of deployment may be based on the desired lesion size and/orthe accuracy of the placement of needle. For example, the same needlemay be used in two different procedures where the variability of thelocation of a target nerve is greater in the first procedure than it isin the second procedure. In such situation, the greater deployment ofthe filaments may be used in the first procedure, whereas in the secondprocedure, a smaller degree of deployment may be used since a smallerlesion may suffice to ensure that the target nerve has been ablated. Foranother example, after placement of the needle during a procedure, theposition of the needle may be determined to be slightly offset from atarget position. In such a case, the filaments may be deployed to agreater degree than would have been required if the needle were placedexactly on target. In such a case, the greater degree of deployment maybe used to compensate for the needle positioning inaccuracy. In such acase, needle repositioning and possible associated trauma may beavoided.

During and/or after advancing the filaments to the deployed position,their positions may be confirmed using an imaging system (e.g., using afluoroscope). Proper filament positioning may also be verified by usingthe needle to stimulate the target nerve. For example, an electricalsignal (e.g., up to about 2 volts applied at about 2 Hz) may be appliedto the needle and the user may observe any related patient movement(e.g., muscle fasciculation in the territory supplied by the nerve). Foranother example, an electrical signal (e.g., up to about 1 volt appliedat about 50 Hz) may be applied to the needle and the patient mayindicate if they feel any associated sensations and their locations toassist in verifying correct needle positioning. Such stimulation(user-observed and/or patient reported) may be used to stimulate atargeted nerve to determine if the deployed position is adequate toachieve denervation of the targeted nerve. In this regard, it isdesirable for the stimulation to affect the targeted nerve. Upondetermination that the target nerve is stimulated, increased energy maybe applied to ablate a volume comprising the target nerve.

Such stimulation may also be used to attempt to stimulate a nerve thatis not targeted for denervation (e.g., a nerve where no denervation isdesired) to determine the position of the needle relative to such anon-targeted nerve. In this regard, if the stimulation signal does notstimulate the non-targeted nerve, the user may determine that theposition of the needle relative to the non-targeted nerve is such thatthe application of ablation energy to the needle will not result insignificant damage to (e.g., ablation of) the non-targeted nerve. If thestimulation stimulates the non-targeted nerve (e.g., as determined byuser observation and/or patient reporting), the needle may berepositioned to avoid damaging the non-targeted nerve. In this regard,it is desirable for the stimulation not to affect the non-targetednerve.

After correct needle positioning has been verified (e.g., by imagingand/or stimulation), an anesthetic may be injected through the needle,for example out of at least one of the fluid port 210, 320, the filamentports 304 a, 304 b, 318 a, 318 b, the lumen 306 c, etc.

After the filaments have been advanced to the desired position, the nextstep may be to apply RF energy to the needle using the interconnected RFgenerator. In embodiments that use a separate RF probe to deliver RFenergy, the RF probe may be inserted into a lumen of the needle prior toapplication of the RF energy. When using such a configuration, theapplication of RF energy may include applying RF energy to the RF probeand conducting the RF energy away from the probe by the tip and/orfilaments.

The resultant RF energy emanating from the tip and/or the filaments maygenerate heat that ablates the target nerve. Such ablation may beachieved by creating a lesion volume that includes the target nerve. Itis desired that the target nerve be completely ablated to preventincomplete neurotomy which may result in dysesthesia and/or patientdiscomfort. For example, a lesion with a maximum cross-sectionaldimension between about 8 mm and about 10 mm may be created. Larger orsmaller lesions may be created by varying filament characteristics(e.g., filament advancement distance) and/or RF energy levels. Thecreated lesion may be offset from the central longitudinal axis of theneedle. The center of the lesion may be distal to the tip of the needle.Of note, since the RF energy is emanating from the tip and filaments, aparticularly sized lesion may be created with a lower peak temperature(the maximum temperature experienced in the patient) than would bepossible if a needle without filaments or without deployed filamentswere to be used to create the same-sized lesion. For example, aparticular lesion may be achieved with the needle with deployedfilaments where the peak temperature is between about 55° C. and about60° C. or less than about 70° C., whereas creation of the same lesionusing a needle without filaments or without deployed filaments couldrequire a peak temperature of about 80° C. Such lower temperaturelesions achievable by a needle with deployed filaments may result ingreater patient safety and/or procedure tolerance.

Before, during, and/or after the application of RF energy, a temperaturesensor (e.g., thermocouple) at or near the tip of the needle may be usedto monitor the temperature at or near the tip. Such readings may be usedas control signals (e.g., a feedback loop) to control the application ofRF energy to the needle. For example, control signals and/or temperaturedata may be used for closed-loop control of the needle 103 by automaticadjustment of a parameter (e.g., frequency, wattage, and/or applicationduration of the RF energy, and/or filament deployment length, needleposition, etc.) upon detection of a temperature. Feedback loopsinvolving the user are also possible. If it is desired to ablateadditional target nerves or to ablate an additional volume to ensureablation of the original target nerve, the spinal RF neurotomy proceduremay continue. In some embodiments, the distal end 402 of the RF probe401 is a dual-purpose wire that can deliver RF energy to the tip and/orthe filaments and that can act as a thermocouple (e.g., havingthermosensing properties).

In embodiments in which the needle is configured to create lesionsoffset from the central longitudinal axis, and an additional targetnerve or target volume is within a volume that may be ablated using theneedle in its current position but in a different rotationalorientation, the procedure may continue as follows. First, after theinitial RF energy application, the filaments may be retracted into theneedle. Once retracted, the needle may be rotated, and the filamentsredeployed. The redeployment may have the same characteristics (e.g.,length of the deployed portions of the filaments) as the originaldeployment or different characteristics. Next, the reoriented needle maybe used to at least partially ablate the additional target nerve ortarget volume. Such retargeting of ablation volumes withoutrepositioning (e.g., without withdrawing the needle from the patient andreinserting), may result in reduced patient trauma as compared to knownspinal RF neurotomy procedures, which may require removal andreinsertion of a needle to achieve lesioning of the second targetvolume. Moreover, such retargeting of ablation volumes withoutrepositioning (e.g., with only rotation of the needle, withoutadditional tissue piercing) may result in the ability to create uniquelyshaped lesions from a single insertion position. Such shaped lesions mayinclude, for example, lesions that are in the shape of two or moreintersecting spheres or oblong spheroids. The steps of retracting thefilaments, rotating the needle, redeploying the filaments, and applyingRF energy may be repeated a plurality of times. In some embodiments, ansecond ablation volume may be defined without rotating the needle, butby different deployment characteristics (e.g., lengths, RF energyparameters, etc.) of the filaments.

In embodiments in which the additional target nerve or target volume isnot within a volume that may be ablated by rotating the needle, theneedle may be repositioned. Such repositioning may include partially orfully removing the needle from the patient and then repositioning theneedle and repeating the herein-described steps. In some embodiments,the second ablation is performed using a different needle (e.g., aneedle with different properties (e.g., longer filaments)) than theoriginal needle.

When no additional ablation is desired, the filaments of the needle maybe retracted, and the needle may be removed from the patient. Afterremoval of the needle, a sterile bandage may be placed over the needleinsertion site or sites. The patient may then be held for observationand recovery from the effects of any sedative that may have beenadministered.

Examples of specific spinal RF neurotomy procedures will now bedescribed. Generally, steps unique to each procedure will be discussedwhile steps common to any spinal RF neurotomy procedure (e.g., sitepreparation such as infiltrating the skin and subcutaneous tissues with1.5% lidocaine to achieve skin anesthesia, nicking the skin tofacilitate needle insertion, insertion monitoring with fluoroscopy,stimulation, etc., filament deployment mechanics, needle removal, andthe like) will not be further discussed. Each of the procedures isdescribed as being performed with a needle comprising two filamentsoffset from the central longitudinal axis, for example as describedherein. It will be appreciated that the variations in needleconfiguration discussed herein may be used in these procedures. Forexample, to increase the offset of the created lesion relative to thecentral longitudinal axis, curved filaments (e.g., as illustrated inFIG. 10) and/or partially insulated filaments (e.g., as illustrated inFIGS. 3H and 3I) may be used to create a lesion different properties(e.g., greater offset from the central longitudinal axis).

1. Lumbar RF Neurotomy of a Medial Branch Nerve Proximate a Lumbar FacetJoint.

This process may include using a needle that enables the creation oflesions that are offset from the central longitudinal axis. Theprocedure will be described as being performed on the L5 vertebra 1101of FIG. 12 and the needle 103 of FIG. 2A. It should be understood thatother embodiments of needles described herein and/or other lumbarvertebra may be used in the described procedure or variations thereof.

The lumbar RF neurotomy process may include positioning the tip 201 ofthe needle 103 (e.g., using fluoroscopic navigation) such that the tip201 is in contact with, or proximate to, the groove 1102 between thetransverse process 1103 and the superior articular process 1104 of thetargeted lumbar vertebra 1101. Such positioning is shown in FIG. 12. Bycontacting the lumbar vertebra 1101, a positive determination of theposition of the needle 103 may be made. By way of example, suchpositioning may be performed such that the needle 103 is within 30° ofbeing perpendicular to the lumber vertebra 1101 at the point of contactwith the lumbar vertebra 1101, or at the point of the lumbar vertebra1101 closest to the tip 201 of the needle 103. Optionally, from such aposition, the needle 103 may be retracted a predetermined amount (e.g.,between about 3 mm and about 5 mm), for example as measured by markers224 on the needle 103, as determined using the collar about theelongated member 203 discussed herein, and/or by fluoroscopicnavigation.

The process may include rotating the needle 103 such that the midpoint502 is oriented toward the superior articular process 1104 and a medialbranch nerve 1105 that is positioned along a lateral face 1106 of thesuperior articular process 1104. Next, the filaments 206 a, 206 b may beadvanced to the deployed position, as shown in FIG. 12. The positions ofthe needle 103 and the deployed filaments 206 a, 206 b may be verifiedusing fluoroscopy and/or patient stimulation (e.g., motor and/orsensory). The RF probe 401 may then be inserted into the lumen 222 suchthat RF energy emanating from the probe 103 will be conducted by the tip201 and filaments 206 a, 206 b to the target medial branch nerve 1105and away from the intermediate branch of the posterior primary ramus.

Next, RF energy may be applied to the RF probe 401. The RF energyemanating from the needle 103 may be preferentially biased toward thetarget medial branch nerve 1105. The lesion created by such a proceduremay, for example, have a maximum cross-sectional dimension of betweenabout 8 mm and about 10 mm, and may ablate a corresponding portion ofthe medial branch nerve 1105, thus denervating the facet joint.

In some embodiments, the needle may be operable to create a generallysymmetric lesion relative to its central longitudinal axis (e.g., asillustrated in FIG. 9). In certain such embodiments, the sequence ofsteps may include insert needle, deploy filaments, and apply RF energy.

In some embodiments, the needle may be inserted to be along the lengthof a portion of the nerve (as illustrated by needle 103′ outlined bybroken lines). Such positioning may be similar to known methods of RFneurotomy performed using needles without filaments. After positioningthe needle, the filaments may be deployed and a lesion may be created.As noted herein, a needle with deployable filaments that is capable ofproducing a lesion equivalent to that of a needle without deployablefilaments may be smaller in diameter than the needle without deployablefilaments. Although positioning of the needle 103′ may be similar toknown processes, the process utilizing the needle 103′ with deployablefilaments may cause less trauma and be safer than procedures using aneedle without deployable filaments due to the smaller size of theneedle with deployable filaments. As discussed herein, the peaktemperatures capable of producing the desired lesion volume may be lesswhen using the needle 103′ with deployable filaments as compared to aneedle without deployable filaments, further contributing to patientsafety. The filaments of the needle 103′ may be partially or fullydeployed to achieve a desired lesion location, shape, and/or size.

It is noted that the illustrated deployment of needle 103 with thefilaments 206 a, 206 b deployed may be used to create a lesion thatapproximates a lesion that would be created with the needle withoutfilaments that is placed in the position of needle 103′ (e.g., parallelto the target nerve 1105). The placement of needle 103 generallyperpendicular to the surface of the L5 vertebra 1101 may be lessdifficult to achieve than the parallel placement of the needle 103′.

2. Sacroiliac Joint (SIJ) RF Neurotomy of the Posterior Rami.

This process may include using a needle that enables the creation oflesions which are offset from the central longitudinal axis. Theprocedure will be described as being performed on the posterior rami1201 of the SIJ of FIG. 12 and using the needle 103 of FIG. 2A. Itshould be understood that other embodiments of needles described hereinand/or other portions of the SIJ may be used in the described procedureor variations thereof.

As part of the SIJ RF neurotomy process, it may be desirable to create aseries of lesions in a series of lesion target volumes 1203 a-1203 hlateral to the sacral foramina 1211, 1212, 1213 of a side of the sacrum1200 to ablate posterior rami 1201 that are responsible for relayingnociceptive signals from the SIJ. Since the exact positions of the rami1201 may not be known, ablating such a series of target volumes 1203a-1203 h may accommodate the variations in rami 1201 positions. Theseries of target volumes 1203 a-1203 h may be in the form of one or moreinterconnected individual target volumes, such as the target volumes1203 a, 1203 b. In some embodiments, the process further comprisesforming a lesion 1208 between the L5 vertebra 1209 and the sacrum 1200to ablate the L5 dorsal ramus.

The SIJ RF neurotomy process may include positioning the tip 201 of theneedle 103 (e.g., using fluoroscopic navigation) such that it is incontact with, or proximate to, and in lateral relation to the S1posterior sacral foraminal aperture (PSFA) 1211 at a first point 1204that is at the intersection of the two target volumes 1203 a, 1203 b.Such positioning may be performed such that the needle 103 is orientedwithin 30° of being perpendicular to the sacrum 1200 at the point ofcontact (or at the point of the sacrum 1200 closest to the tip 201 ofthe needle 103). By contacting the sacrum 1200, a positive determinationof the position of the needle 103 may be made. Optionally, from such aposition, the needle 103 may be retracted a predetermined amount (e.g.,between about 3 mm and about 5 mm) as measured, for example, by markers224 on the needle 103, as determined using the collar about theelongated member 203 discussed herein, and/or by fluoroscopicnavigation. For example, a contralateral posterior oblique view may beobtained to ascertain that the tip 201 has not entered the spinal canal.For example, a fluoroscopic view may be obtained looking down the lengthof the needle 103 to verify that the needle 103 is properly offset fromthe S1 PSFA 1211 and/or a fluoroscopic view may be obtained lookingperpendicular to the central longitudinal axis 223 to verify that theneedle 103 is not below the surface of the sacrum (e.g., in the S1 PSFA1211). An electrical signal may be applied to the needle 103 tostimulate nerves proximate to the tip 201 to verify correct needle 103placement.

The SIJ RF neurotomy process may include rotating the needle 103 suchthat the midpoint 502 is oriented toward the first target volume 1203 ain the direction of arrow 1205 a. Next, the filaments 206 a, 206 b maybe advanced to the deployed position. The position of the needle 103 andthe deployed filaments 206 a, 206 b may be verified using fluoroscopyand/or stimulation (e.g., motor and/or sensory). The RF probe 401 may beinserted into the lumen 222 before, during, and/or after filamentdeployment such that RF energy emanating from the needle 103 will beconducted by the tip 201 and the filaments 206 a, 206 b to the firsttarget volume 1203 a. Next, RF energy may be applied to the RF probe401. The RF energy emanating from the needle 103 may be preferentiallybiased toward the first target volume 1203 a. The lesion created by suchan application of RF energy may, for example, have a maximumcross-sectional dimension of between about 8 mm and about 10 mm, and mayablate a corresponding portion of the rami 1201.

Next, the filaments 206 a, 206 b may be retracted and the needle 103 maybe rotated approximately 180° such that the midpoint 502 is orientedtoward the second target volume 1203 b in the direction of arrow 1205 b.Optionally, some lateral repositioning of the needle may performed(e.g., without any needle pull back or with a small amount of needlepull back and reinsertion). Next, the filaments 206 a, 206 b may beadvanced to the deployed position. The position of the needle 103 andthe deployed filaments 206 a, 206 b may be verified using fluoroscopyand/or stimulation (e.g., motor and/or sensory). The RF probe 401 mayremain in the lumen 222 during the repositioning, or may be removed andthen reinserted. Next, RF energy may be applied to the RF probe 401 tocreate a lesion corresponding to the second target volume 1203 b.

In this regard, with a single insertion of the needle 103, twointerconnected lesions (which may also be considered to be a singleoblong lesion) may be created. Compared to methods in which an RF probemust be repositioned prior to each application of RF energy, the numberof probe repositioning steps may be greatly reduced, reducing patienttrauma and procedure duration. In this regard, a continuous region oflesioning may be achieved about the S1 PSFA 1211 such that the lesionoccupies a volume surrounding the S1 PSFA 1211 from about the 2:30 clockposition to about the 5:30 clock position (as viewed in FIG. 13). Suchlesioning may help to achieve denervation of the posterior ramiproximate to the S1 PSFA 1211.

The herein procedure may be repeated as appropriate to create lesionscorresponding to the entire series of target volumes 1203 a-1203 h, thusdenervating the SIJ. For example, a first insertion may ablate thevolumes 1203 a, 1203 b, a second insertion may ablate the volumes 1203c, 1203 d, a third insertion may ablate the volumes 1203 e, 1203 f, anda fourth insertion may ablate the volumes 1203 g, 1203 h. In thisregard, a similar continuous region of lesioning may be achieved aboutthe S2 PSFA 1212 and a region of lesioning from about the 12:00 clockposition to about the 3:00 clock position (as viewed in FIG. 13)relative to the S3 PSFA may be achieved about the S3 PSFA 1213. A lesion1208 may also be created at the base of the superior articular processof the L5 1209 dorsal ramus in the grove between the superior articularprocess and the body of the sacrum. The needle 103 may be insertedgenerally perpendicular to the plane of FIG. 13 to produce the lesion1208.

In some embodiments, three or more lesions may be created with a needlein a single position. For example, a needle positioned at a point 1206proximate to three target volumes 1203 c, 1203 d, 1203 e, may beoperable to create lesions at each of the three target volumes 1203 c,1203 d, 1203 e, thus further reducing the number of needlerepositionings.

In some embodiments, each individual lesion corresponding to the seriesof target volumes 1203 may be created using a needle with deployablefilaments in which the needle is repositioned prior to each applicationof RF energy. In certain such embodiments, the sequence of steps may beinsert needle, deploy filaments, apply RF energy, retract filaments,reposition needle, and repeat as appropriate to create each desiredlesion. Such a procedure may be conducted, for example, using a needlecapable of producing a lesion symmetric to a central longitudinal axisof the needle (e.g., the needle of FIG. 9).

3. Thoracic RF Neurotomy of a Medial Branch Nerve.

This process may include using a needle that enables the creation oflesions which are offset from the central longitudinal axis of theneedle. Successful treatment of thoracic z-joint pain usingradiofrequency ablation of relevant medial branch nerves can bechallenging owing to the inconsistent medial branch location in theintertransverse space, especially levels T5-T8. A needle withoutfilaments is generally positioned at multiple locations in theintertransverse space to achieve sufficient tissue ablation forsuccessful medial branch neurotomy. The procedure will be described asbeing performed on an intertransverse space between adjacent vertebrae1301, 1302 of the T5 to T8 thoracic vertebrae using FIG. 14 and theneedle 103 of FIG. 2A. It should be understood that other embodiments ofneedles described herein and/or other vertebrae may be used in thedescribed procedure or variations thereof.

The process may include obtaining a segmental anteroposterior image attarget level defined by counting from T1 and T12. This may be followedby obtaining an image that is ipsalateral oblique about 8° to about 150off-sagittal plane of the spine to visualize costotransverse jointlucency clearly. This can allow improved visualization of thesuperior-lateral transverse process, especially in osteopenic patients.The angle can aid in directing the probe to a thoracic anatomic safezone medial to the lung, reducing risk of pneumothorax.

The skin entry site for the needle 103 may be over the most inferioraspect of transverse process slightly medial to costotransverse joint.Inserting the needle 103 may include navigating the device over thetransverse process over the bone to touch the superior transverseprocess slightly medial to the costotransverse joint. The process mayinclude checking anteroposterior imaging to demonstrate that the tip 201of the needle 103 is at the superolateral corner of the transverseprocess. The process may also include checking a contralateral obliqueimage view (e.g., at 15°) to demonstrate, for example in “Pinnochio”view, the target transverse process in an elongate fashion. This viewcan be useful for showing the tip 201 of the needle 103 in relationshipto the superolateral margin of the transverse process subadjacent to thetargeted medial branch nerve. The process may include retracting the tip201 slightly (e.g., about 1 mm to about 3 mm). In some embodiments,retracting the tip 201 positions the ports at the superior edge of theprocess (e.g., visible with a radiopaque marker).

In some embodiments, medial to lateral placement may be performedentering the skin beneath the segmental spinous process, and navigatingthe needle 103 over the transverse process to contact a point justproximal to the superolateral corner of the transverse process. The tip201 may then be advanced to approximate the exit port 304 a, 304 b ofthe filaments 206 a, 206 b with the superior margin of the transverseprocess, and the filaments 206 a, 206 b are deployed.

The process may include rotating the needle 103 such that the midpoint502 is oriented toward the intertransverse space between the vertebrae1301, 1302 and the medial branch nerve 1303 that is positioned therein.Next, the filaments 206 a, 206 b may be advanced ventral into theintertransverse space between the vertebrae 1301, 1302 to the deployedposition. The position of the needle 103 and deployed filaments 206 a,206 b may be verified using fluoroscopy (e.g., using lateral imaging)and/or stimulation (e.g., motor and/or sensory), for example to rule outproximity to ventral ramus. In some embodiments, the filaments 206 a,206 b are deployed in a ventral direction in the intratransverse space,which may be confirmed by obtaining lateral. The RF probe 401 may beinserted into the lumen 222 such that RF energy emanating from the probe103 will be conducted by the tip 201 and the filaments 206 a, 206 b tothe target medial branch nerve 1303. Next, RF energy may be applied tothe RF probe 401. The RF energy emanating from the needle 103 may bepreferentially biased toward the volume between the vertebrae 1301,1302. The lesion created by such a procedure may, for example, have amaximum cross-sectional dimension of between about 8 mm and about 10 mm,and may ablate a corresponding portion of the medial branch nerve 1303.This method can treat the medial branch as it curves out of theintratransverse space emerging into the posterior compartment of theback. The directional bias of the lesion may advantageously heat towardsthe target and away from the skin.

It is noted that thoracic RF neurotomy performed on other thoracicvertebrae may call for different sizes of lesions. For example, thoracicRF neurotomy performed on the T3-T4 vertebrae may require a smallerlesion volume than the herein-described procedure, and thoracic RFneurotomy performed on the T1-T2 vertebrae may require a still smallerlesion volume. As described herein, the deployment of the filaments ofthe needle 103 may be varied to achieve such desired target lesionvolumes, or different needles may be used (e.g., having shorterfilaments in the fully deployed position).

4. Cervical Medial Branch RF Neurotomy.

Embodiments of needles described herein (e.g., the needle 103 of FIG.2A) are capable of creating a volume of tissue ablation necessary forcomplete denervation of the cervical zygapophyseal joints, including theC2/3 cervical zygapophyseal joint (z-joint). Tissue ablation forcervical z-joint using embodiments of needles described herein may beaccomplished using a single placement and single heating cycle. Suchsingle placement and single heating cycle may avoid unnecessary tissuedamage from multiple placements of a filament-free needle, andunintended injury to collateral tissue caused by excessive lesioning.The zone of ablation can be designed to provide sufficient and necessarytissue coagulation for a successful procedure, and thus may be expectedto improve the outcomes of patients undergoing spinal radiofrequencyneurotomy.

A cervical medial branch RF neurotomy procedure will be described asbeing performed on the third occipital nerve at the C2/3 z-joint usingthe needle 103 as shown in FIG. 15. In FIG. 15, the needle 103 ispositioned between the C2 vertebra 1401 and the C3 vertebra 1402.

In a first step, the patient may be placed in a prone position on aradiolucent table suited to performing fluoroscopically guided spinalprocedures. Sedation may be administered. The patient's head may berotated away from the targeted side. Sterile skin prep and draping maybe performed using standard well-described surgical techniques.

For Third Occipital Nerve (TON) ablation (C2/3 joint innervation) thelateral aspect of the C2/3 Z-joint is located under either parasagittalor, alternatively, ipsilateral oblique rotation of less than or equal toabout 30° (e.g., between about 20° and about 30°) of obliquity relativeto the true sagittal plane of the cervical spine. The skin entry pointmay be infiltrated with local anesthetic. Then, the tip 201 of theneedle 103 is moved over the most lateral aspect of bone of thearticular pillar at the juncture of the C2/3 z-joint to a first positioncontacting bone proximate to the most posterior and lateral aspect ofthe z-joint complex, for example using a “gun-barrel” technique to touchthe most lateral and posterior aspect of the articular pillar at thepoint of maximal concavity for level below C2/3 or at the point ofmaximal convexity at the C2/3 level when targeting the TON.

Once boney contact is made, the needle 103 may be retracted apredetermined distance (e.g., between about 1 mm and about 3 mm) and thefilaments are deployed towards the lateral aspect of the C2/3 z-joint.The filaments will spread to encompass anticipated rostrocaudalvariation in the target nerve location. The angle of the filaments withrespect to the tip may effectively cover the ventral aspect of thearticular pillar up to the border of the superior articular process,thus incorporating benefits of a 30° oblique pass. The needle 103 may berotated about a central longitudinal axis prior to filament deploymentto ensure that deployment will occur in the desired direction.

Multiplanar fluoroscopic imaging may then be employed to verify that thetip and the filaments are positioned as desired. For example, it may beverified that the filaments are positioned straddling the lateral jointlucency, and posterior to the C2/3 neural foramen. Useful imaging anglesinclude anterior-posterior (AP), lateral, and contralateral oblique(Sluijter) views. To further verify adequate positioning of the needle103, motor stimulation may be performed by delivering a voltage (e.g.,up to about 2 volts) at about 2 Hz to the tip 201 and filaments and/orsensory stimulation may be performed at appropriate voltage (e.g.,between about 0.4 volts and about 1 volt) and frequency (e.g., about 50Hz).

After position verification, RF energy may be applied to the tip and theplurality of filaments to generate heat that ablates a portion of thethird occipital nerve. The cross-sectional dimensions of the lesion(e.g., between about 8 mm and about 10 mm) can incorporate all medialbranches as well as the TON, which has a nerve diameter of about 1.5 mm.The directional nature of the lesion, offset towards the filaments,provides a beneficial measure of safety regarding undesired thermaldamage to the skin and to collateral structures. Safety concerns may befurther satisfied by fluoroscopic observation of the filaments dorsal tothe intervertebral foramen and/or lack of ventral ramus activationduring stimulation (e.g., with 2 Hz and 2 volts). After lesioning, thedevice may be removed. For levels below the C2/3 z-joint, the proceduremay be similar than as described herein with respect to the thirdoccipital nerve, with the exception that the initial boney contacttarget is at the waist of inflection point of the articular pillar.

Other spinal RF procedures may also benefit from the asymmetricalapplication of RF energy from embodiments of the needles describedherein. Such asymmetry may, for example, be used to project RF energy ina desired direction and/or limit the projection of RF energy inundesired directions. The configuration of the filaments may be selectedfor a particular application to produce a desired size, shape, and/orlocation (relative to the needle tip) of a lesion within the patient.The location of the lesion may be offset distally and/or laterally fromthe tip of the needle as desired for a particular application.

It will be appreciated that the delivery of RF energy to tissue in theanatomy can be practiced for a multitude of reasons, and embodiments ofthe needles described herein may be adapted (e.g., modified or scaled)for use in other medical procedures. For example, embodiments of needlesdescribed herein could be used to deliver RF energy as a means tocauterize “feeder vessels,” such as in bleeding ulcers and/or inorthopedic applications. For another example, embodiments of the needlesdescribed herein could be adapted for use in procedures such as cardiacablation, in which cardiac tissue is destroyed in an effort to restore anormal electrical rhythm in the heart. Certain such uses could furtherbenefit from the ability of embodiments of needles described herein todeliver fluid through a lumen since, for example, emerging procedures incardiac therapy may require the ability to deliver stem cells, vascularendothelial growth factor (VEGF), or other growth factors to cardiactissue. The ability to steer embodiments of the needle described hereinmay provide significant benefit in the field of cardiovascular drugdelivery.

For example, a needle may be adapted for use in vertebral disc heating.A primary longer needle (e.g., having a length of about 15 cm and a tipwith an uninsulated active portion having a length of about 2 mm,although other dimensions are also possible), is placed into the postposterolateral margin of a painful intervertebral disc, for example asdescribed elsewhere for provocation discography and/or therapeutic discaccess procedures such as Dekompressor® discectomy and disc biacuplasty.Once positioned in the posterior annulus, as confirmed withfluororscopy, tactile feedback, and/or characteristic impedancereadings, a single filament is deployed to traverse the posteriorannulus in a lateral to medial fashion in the lamella of the annulusfibrosis, for example as illustrated in FIG. 18A, which is an axial viewof posterior oblique needle entry with the main axial tip in theposterior annulus and deployed a filament moving lateral to medial inthe lamella of the posterior annulus, and FIG. 18B, which is a saggitalview with a filament moving across the posterior annulus from lateral tomedial.

In some embodiments, the filament may act as a thermocouple (e.g.,comprising a material having thermosensing properties as describedherein) to allow precise measurement of actual temperatures of theannulus. In some embodiments, the filament includes a lumen configuredto allow injection of therapeutic substances (e.g., methylene-blue) uponwithdrawal for substantially simultaneous chemo-thermo-neurolysis and/orto allow injection of contrast agent for confirmation of intraannularplacement that is definite, for example as opposed to potentiallydangerous placement in the spinal canal or futile placement in thenucleus pulposus. In some embodiments, the filament has an exit anglegreater than about 30°. In some embodiments, the filament includes abeveled Quincke tip oriented to bias away from the spinal canal uponadvancement, as needles in tissue track away from bevel angles. In someembodiments, the deployed filament has a length between about 10 mm andabout 12 mm. In some embodiments, the needle does not include a lumenfor injection of liquid. In certain such embodiments, the area notoccupied by a lumen may be used for the filament, which may be morecomplicated due to use as a thermocouple and/or including a lumen.

Bipolar or monopolar RF energy is applied to the tip and to thefilament, creating a zone of therapeutic heating across the posteriordisc annulus and resulting in destruction of the pain fibers inapproximately the outer third of the annulus. The procedure may berepeated on the opposite side. In some embodiments, the needle includesa plurality of deployable filaments, and gap between the filaments(e.g., the distance 604 in FIG. 6) is between about 2 mm and about 10mm, between about 4 mm and about 8 mm, between about 5 mm and about 7 mm(e.g., about 6 mm), combinations thereof, and the like.

Example 1

Sections of raw muscle tissue were allowed to equilibrate to 37° C. in adistilled water bath. A needle with tines deployed was positioned tocontact the tissue surface in 10 trials and was inserted into tissue in10 trials. A Radionics RFG 3C RF generator energy source was set at 75°C. for 80 seconds. Propagation of tissue coagulation was documented withvideo and a calibrated Flir T-400 thermal camera. Tissue samples weresectioned and coagulation zones measured. Infrared observationdemonstrated symmetric and homogenous lesion progression without hotspots or focal over-impeding. Calculated volume averaged 467±71mm³/lesion. Topography was elongate spheroid offset from the centralaxis toward the filaments. Thus, the needle reliably produced lesionsthat are potentially useful in spinal applications.

Example 2

A 47 year-old male with recalcitrant right-sided lumbar zygapophysialjoint pain presented for radiofrequency medial branch neurotomy. Thediagnosis had been made by greater than 80% relief documented followingboth intraarticular z-joint injection and confirmatory medial branchblocks.

The patient was placed in a prone position on the fluoroscopy table andstandard monitors were applied. No sedation was administered. The lumbarregion was extensively prepped with chlorhexidine-alcohol and draped inroutine sterile surgical fashion. The C-arm was adjusted to visualize atrue AP of the L4/5 intervertebral disc space with vertebral end platessquared-off, and spinous process positioned between the pedicle shadows.The C-arm was rotated 30°-40° ipsilateral to the target joint until thebase of the SAP of the L4 and L5 were clearly visualized. A target pointwas identified at the midpoint of the base of the SAP, and the overlyingskin and subcutaneous tissues were infiltrated with 1.5% lidocaine. Asmall skin nick was made with an 18-gauge needle to facilitate placementof an embodiment of the needles described herein. Once skin anesthesiawas established, the needle, with filaments in the retracted position,was advanced using a gun-barrel approach until boney contact was madewith the base of the SAP. The needle was then retracted off the boneslightly, and using the indentation on the hub for orientation, theactuator was rotated 360° to fully deploy the filaments. Filaments werefelt to touch bone at the base of the SAP. AP, oblique, and lateralimages were obtained to document the placement and to confirm that thefilaments were directed toward the SAP. In this position, the lesion wasbiased to cover any variant medial branch situated higher up the SAP. Ifthe filaments were not directed in an ideal fashion, they wereretracted, the device was rotated as necessary, and the filaments wereredeployed. Motor stimulation at a frequency of 2 Hz up to 2 volts wasincrementally administered with brisk activation of the multifidus, butwith no activation of any ventral root inenervated musculature. Sensorystimulation at 50 Hz at 0.6 volts elicited a concordant aching in thedistribution of the patient's pain. A 22-gauge, 10 cm, 10 mm active tipRFK connected to an independently grounded second RF generator wasplaced sequentially at the following targets for in vivo thermometry:(1) Most inferior and dorsal location in the supra-segmental neuralforamen evaluating the potential for thermal injury of spinal nerve; (2)At a point lateral on the transverse process approximating the locationof intermediate/lateral branches of the posterior primary rami; (3) Ator near the central axis of the needle during stable heating; (4) On theSAP at the base and successively higher on mamilliary process toevaluate heating on the region of potential MB variation (up the SAP).The process was then repeated for denervation of the L5.

Following the confirmation of safe and optimal placement by fluoroscopyand stimulation, the heating protocol was initiated based on previousbranch testing in egg white and chicken meat. The protocol included: 45°C. for 15-30 seconds, await rapid temperature increase signaling primaryconsolidation of heating and biophysical changes around core axis; 50°C. for 15 seconds; 60° C. for 15 seconds; 70° C. for 10 seconds torecord foraminal temperatures only.

Generator parameters during ablation were appropriate and within thetolerance range for a generically programmed RF generator. The lowerstarting impedance, relative to a monopolar needle, may be explained bygreatly increased conductive surface of the needle. Brief temperaturefluctuation was noted as the lesion propagated to encompass the centralaxis housing the thermocouple. It is anticipated that changes in thegenerator software may be useful to support various embodiments of thedescribed device. Impedance readings were 75 ohms to 250 ohms. Powerranges were 2 watts to 11 watts, typically 3 watts to 4 watts after 10seconds into the procedure.

The thermal mapping results were as follows: (1) Perineural temperatures(neurogram obtained via TC2) at the supra-adjacent spinal nerve did notincrease from a 38° C. baseline; (2) Temperature readings from the TC2placed near the central axis of the needle reflected deliveredtemperature from the generator; (3) Temperature readings from the baseof the SAP to relatively dorsal position on the SAP exceed theneuroablative threshold of 45° C.

The patient experienced minimal discomfort following the procedure. Forthe sake of full disclosure, it is noted that the patient is an inventorof the present application. No postoperative analgesics were required.The patient reported near complete relieve of his right-sided low backpain within 10 days of the procedure. Bilateral paraspinal EMG at L3,L4, and L5 was performed 20 days after the RF procedure, as documentedin Table 1:

TABLE 1 Paraspinal EMG Side Muscle Nerve Root Ins Act Fibs Psw Left L3Parasp Rami L3 Nml Nml Nml Left L4 Parasp Rami L4 Nml Nml Nml Left L5Parasp Rami L5 Nml Nml Nml Right L3 Parasp Rami L3 Nml Nml Nml Right L4Parasp Rami L4 *Incr *1+ *1+ Right L5 Parasp Rami L5 *Incr *1+ *1+*Needle evaluation of the right L4 paraspinal and the right L5paraspinal muscles showed increased insertional activity and slightlyincreased spontaneous activity. *All remaining muscles showed noevidence of electrical instability.

There was electrodiagnostic evidence of active and acute denervation ofthe right lumbar paraspinals at the L4 and L5 levels. The contralateralleft-sided paraspinals appeared normal. These findings are consistentwith the clinical history of recent right lumbar radiofrequencyrhizotomy.

Thus, the needle was safely and effectively used to accomplish lumbarmedial branch neurotomy. Thermal mapping demonstrated a safe andeffective isotherm consistent with bench predictions, and EMG of thelumbar paraspinals demonstrated objective evidence of medial branchcoagulation. The needle appears to extend beneficially on existingtechniques and technology. For a first example, facilitated placementfor lumbar medial branch neurotomy using “down-the-beam” technique akinto diagnostic medial branch block. This approach can be applied to otherspinal targets such as cervical z-joint neurotomy, thoracic z-jointneurotomy, sacroiliac joint denervation, central innercation of thelateral C1-2 joint, RF neurotomy thoracic sympathetic chain, RFneurotomy sphlancnic chain at T10, 11, 12, RF neurotomy lumbarsympathetic pain, and RF neurotomy superior hypogastric plexus. For asecond example, lab testing and in vivo thermal data demonstrates alarge volume suited for efficiently dealing with common variations inafferent sensory pathways. The lesion can be directed relative to thecentral longitudinal axis of the needle toward targets and away fromsensitive collateral structures. For a third example, the needle candeliver meaningful motor and/or sensory stimulation for documentation ofsafe placement. For a fourth example, lesion topography is driven byneedle design, and does not require high temperatures (e.g., greaterthan 80° C.) for extended times. It is believed that 60° C. for 60seconds is adequate for most targets. Reduced procedural time and/orlower temperatures should translate to fewer complications, expeditedrecovery, and/or diminished incidence of postoperative painsyndromes/dysesthesias. For a fifth example, relative to other largefield lesion technology, the needle is of a uncomplicated and robustdesign, does not require additional support equipment, and is economicalto manufacture.

Although this invention has been disclosed in the context of certainembodiments and examples, it will be understood by those skilled in theart that the invention extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses of theinvention and obvious modifications and equivalents thereof. Inaddition, while several variations of the embodiments of the inventionhave been shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the invention. It should be understood that various featuresand aspects of the disclosed embodiments can be combined with, orsubstituted for, one another in order to form varying modes of theembodiments of the disclosed invention. Thus, it is intended that thescope of the invention herein disclosed should not be limited by theparticular embodiments described herein.

What is claimed is:
 1. A radiofrequency neurotomy needle operable with aradiofrequency probe, the radiofrequency neurotomy needle comprising: aconductive portion at a distal end of the radiofrequency neurotomyneedle; a tip configured to pierce tissue of a patient; an elongatemember comprising a lumen configured to accept the radiofrequency probetherein such that the radiofrequency probe physically contacts and iselectrically connected to the conductive portion, the tip being at adistal end of the elongate member; a filament electrically connected tothe conductive portion and the tip due to physical contact of conductivematerials at the distal end of the radiofrequency neurotomy needle suchthat the filament and the tip operate together as a single electrode,the filament being movable between a retracted position, in which thefilament is at least partially in the elongate member, and a deployedposition, in which at least a portion of the filament is out of theelongate member; and an actuator interconnected to the filament to movethe filament between the retracted position and the deployed position,wherein the filament and the tip are configured to transmitradiofrequency energy from the radiofrequency probe when the filament isin the deployed position and the radiofrequency probe is accepted in thelumen and is in physical contact with the conductive portion.
 2. Theradiofrequency neurotomy needle of claim 1, wherein the filament isformed of one of the conductive materials and the tip is formed ofanother of the conductive materials, and wherein the conductivematerials of the filament and the tip are in physical contact when thefilament is in the deployed position.
 3. The radiofrequency neurotomyneedle of claim 2, wherein the tip comprises the conductive portion atthe distal end of the radiofrequency neurotomy needle, and wherein theconductive portion is configured to physically contact the distal end ofthe radiofrequency probe when the radiofrequency probe is accepted inthe lumen.
 4. The radiofrequency neurotomy needle of claim 1, whereinthe tip comprises the conductive portion at the distal end of theradiofrequency neurotomy needle.
 5. The radiofrequency neurotomy needleof claim 4, wherein the conductive portion is configured to physicallycontact the distal end of the radiofrequency probe when theradiofrequency probe is accepted in the lumen.
 6. The radiofrequencyneurotomy needle of claim 4, wherein the tip comprises a tip lumen thatis configured to receive the distal end of the radiofrequency probe. 7.The radiofrequency neurotomy needle of claim 1, wherein the needlefurther comprises a tube that is separate from the elongate member, andwherein the tube is positioned within the elongate member.
 8. Theradiofrequency neurotomy needle of claim 7, wherein the lumen is withinthe tube.
 9. The radiofrequency neurotomy needle of claim 7, wherein thetube comprises the conductive portion of the needle.
 10. Theradiofrequency neurotomy needle of claim 1, wherein the tip and theelongate member are a single unitary structure or are separatecomponents that are fixedly interconnected.
 11. The radiofrequencyneurotomy needle of claim 1, further comprising an additional filamentelectrically connected to the conductive portion such that bothfilaments and the tip operate together as the single electrode, whereinthe additional filament is interconnected to the actuator such that bothfilaments are deployed and retracted by the actuator.
 12. Theradiofrequency neurotomy needle of claim 11, wherein when the filamentsare deployed, the tip and the filaments are configured to produce alesion at a target volume of tissue within the patient.
 13. Theradiofrequency neurotomy needle of claim 12, wherein when the tip andthe filaments are configured to produce the lesion so as to beasymmetrical and offset relative to the central longitudinal axis of theradiofrequency neurotomy needle.
 14. The radiofrequency neurotomy needleof claim 12, wherein when the filaments are deployed, distal tips of thefilaments are distal to the tip of the radiofrequency neurotomy needlesuch that the filaments and the tip are configured to produce the lesionso as to be distally offset from the tip of the radiofrequency neurotomyneedle.
 15. The radiofrequency neurotomy needle of claim 12, wherein thetip and the filaments are configured to operate together as the singleelectrode in a monopolar mode to produce the lesion to have a volumebetween about 250 mm³ and about 750 mm³.
 16. The radiofrequencyneurotomy needle of claim 12, wherein when the target volume includes atarget nerve such that formation of the lesion ablates at least aportion of the target nerve to inhibit the ability of the target nerveto transmit pain signals.
 17. The radiofrequency neurotomy needle ofclaim 1, wherein the lumen is further configured to accept theradiofrequency probe therein such that a distal end of theradiofrequency probe is proximate the tip when the radiofrequency probephysically contacts and is electrically connected to the conductiveportion.
 18. The radiofrequency neurotomy needle of claim 1, furthercomprising a fitting configured to provide a connection to a fluidsource for injection of fluid through the lumen.
 19. The radiofrequencyneurotomy needle of claim 18, wherein the radiofrequency neurotomyneedle is operable in a first state in which the radiofrequency probe isfully separated from the radiofrequency neurotomy needle in anon-inserted state and in which the fitting is connected to the fluidsource for injection of fluid through the lumen, and wherein theradiofrequency neurotomy needle is operable in a second state in whichthe fitting is disconnected from the fluid source and in which theradiofrequency probe is inserted through the fitting into the lumen fordelivery of the radiofrequency energy.
 20. The radiofrequency neurotomyneedle of claim 1, wherein the actuator is configured to rotate aboutthe central longitudinal axis to move the filament between the retractedposition and the deployed position.
 21. The radiofrequency neurotomyneedle of claim 1, wherein a distal tip of the filament is closer to acentral longitudinal axis of the radiofrequency neurotomy needle whenthe filament is in the retracted position as compared with when thefilament is in the deployed position.
 22. The radiofrequency neurotomyneedle of claim 1, wherein the filament and the tip are configured tooperate together as the single electrode in a monopolar mode when theradiofrequency probe is accepted in the lumen and is in physical contactwith the conductive portion.
 23. A system comprising: the radiofrequencyneurotomy needle of claim 1; and the radiofrequency probe.
 24. Thesystem of claim 23, further comprising a radiofrequency generator and areturn electrode pad that is configured to be attached to the patient,wherein the filament and the tip are configured to operate together asthe single electrode in a monopolar mode when the radiofrequency probeis accepted in the lumen and is in physical contact with the conductiveportion and when the electrode pad is attached to the patient tocomplete a circuit from the radiofrequency generator, through theradiofrequency probe, through the needle, through a portion of thepatient, through the return electrode pad, and to the radiofrequencygenerator.
 25. A radiofrequency neurotomy needle operable with aradiofrequency probe, the radiofrequency neurotomy needle comprising: atip comprising a conductive material, the tip being configured to piercetissue of a patient; a tube comprising a conductive material, the tubebeing configured to accept the radiofrequency probe therein; a filamentcomprising a conductive material, wherein the tip, the tube, and thefilament are electrically connected at a distal end of theradiofrequency neurotomy needle due to physical contact, at the distalend of the radiofrequency neurotomy needle, of each of the conductivematerials with at least one of the other conductive materials, such thatthe filament and the tip are operative together as a single electrode,the filament being movable between a retracted position and a deployedposition, a distal tip of the filament being closer to a centrallongitudinal axis of the radiofrequency neurotomy needle when thefilament is in the retracted position as compared with when the filamentis in the deployed position; and an actuator interconnected to thefilament to move the filament between the retracted position and thedeployed position, wherein the filament and the tip are configured totransmit radiofrequency energy from the radiofrequency probe when thefilament is in the deployed position and the radiofrequency probe isaccepted in the lumen and in physical contact with at least one of theconductive materials at the distal end of the radiofrequency neurotomyneedle.
 26. The radiofrequency neurotomy needle of claim 25, wherein thetube is an elongate member, and wherein the tip is at the distal end ofthe elongate member.
 27. The radiofrequency neurotomy needle of claim25, further comprising an elongate member, the tip being at a distal endof the elongate member, wherein the tube is separate from the elongatemember and is positioned within the elongate member.
 28. Theradiofrequency neurotomy needle of claim 25, wherein the tip comprises alumen that is configured to receive the distal end of the radiofrequencyprobe.
 29. A radiofrequency neurotomy needle operable with aradiofrequency probe, the radiofrequency neurotomy needle comprising: anelongate member comprising a lumen configured to accept theradiofrequency probe therein; a tip coupled to a distal end of theelongate member and being configured to pierce tissue of a patient, thetip comprising a conductive material configured to physically contact adistal end of the radiofrequency probe when the radiofrequency probe isaccepted in the lumen; a filament comprising a conductive material, thefilament being electrically connected to the tip by way of physicalcontact with the tip at a distal end of the radiofrequency neurotomyneedle such that the filament and the tip are operative together as asingle electrode, the filament being movable between a retractedposition, in which the filament is in a cross-sectional envelope of thetip, and a deployed position, in which a portion of the filament isoutside the cross-sectional envelope of the tip; and an actuatorinterconnected to the filament to move the filament between theretracted position and the deployed position, wherein the filament andthe tip are configured to transmit radiofrequency energy from theradiofrequency probe when the filament is in the deployed position andthe radiofrequency probe is accepted in the lumen and in physicalcontact with the conductive material of the tip.